All practice questions

Question 761Question →

Paramedics deliver a 68-year-old nursing home resident to the acute care bay after staff found him profoundly lethargic amid multiple episodes of bilious emesis over the preceding 48 hours. Medical history is significant for heart failure with preserved ejection fraction, severe osteoarthritis, and recently diagnosed type 2 diabetes mellitus. On initial assessment, he is obtunded but protects his airway.

Vitals:

Parameter	Value
Temperature	36.8°C (98.2°F)
Heart rate	118/min
Blood pressure	88/54 mm Hg
Respiratory rate	10/min
SpO2	93% (room air)

Laboratory data:

Test	Result
Sodium	142 mEq/L
Potassium	3.1 mEq/L
Chloride	90 mEq/L
Bicarbonate	16 mEq/L
Blood urea nitrogen	58 mg/dL
Creatinine	2.7 mg/dL
Glucose	512 mg/dL

Arterial blood gas (room air):

Parameter	Value
pH	7.23
PaO2	74 mm Hg
PaCO2	40 mm Hg

Assuming a normal reference anion gap of 12 mEq/L and a normal reference serum bicarbonate of 24 mEq/L, what is this patient's delta ratio ( $\Delta AG / \Delta HCO_3^-$ )?

Show answer & explanation

Answer: 3

Answer

The patient's calculated delta ratio is 3.0.

This patient presents with a severe triple acid-base disorder: high anion gap metabolic acidosis (likely diabetic ketoacidosis or lactic acidosis from hypoperfusion), metabolic alkalosis (from severe vomiting), and respiratory acidosis (from obtundation causing hypoventilation). The delta ratio compares the rise in the anion gap (

\Delta AG

) to the fall in bicarbonate (

\Delta HCO_3^-

). For every 1 mEq/L increase in unmeasured acids, the bicarbonate should theoretically fall by 1 mEq/L, yielding a ratio of 1.0 (or up to 2.0 in lactic acidosis due to varying intracellular buffering efficiency). A ratio

> 2.0

indicates that the bicarbonate has not fallen as much as expected given the massive acid load. In this patient, the massive acid load (

\Delta AG = 24

) only dropped the bicarbonate by 8 mEq/L. This proves the existence of a concurrent metabolic alkalosis (from the loss of gastric

HCl

) generating additional bicarbonate that masks the severity of the acidosis. Additionally, Winter's formula predicts a PaCO2 of

1.5(16) + 8 = 32 \pm 2

mm Hg; the measured PaCO2 of 40 mm Hg confirms a concurrent respiratory acidosis.

Step-by-Step Solution

1

Calculate the serum anion gap using the formula

AG = Na^+ - (Cl^- + HCO_3^-)

.

142 - (90 + 16) = 142 - 106 = 36

mEq/L.

The first step in evaluating any metabolic acidosis is determining if unmeasured anions are present.

2

Calculate the change in anion gap (

\Delta AG

).

36 - 12 = 24

mEq/L.

This determines the exact magnitude of excess unmeasured acid that has accumulated in the blood above the normal baseline.

3

Calculate the change in bicarbonate (

\Delta HCO_3^-

).

24 - 16 = 8

mEq/L.

This determines how much the serum bicarbonate has dropped from its baseline normal value due to buffering the acid load.

4

Calculate the delta ratio by dividing

\Delta AG

by

\Delta HCO_3^-

.

24 / 8 = 3.0

.

Evaluating the ratio between the rise in unmeasured acids and the fall in bicarbonate helps identify concurrent secondary metabolic acid-base disorders.

Key Concept

In patients with a high anion gap metabolic acidosis, the delta ratio (

\Delta AG / \Delta HCO_3^-

) is calculated to uncover hidden concurrent metabolic disorders. A ratio greater than 2.0 indicates a superimposed metabolic alkalosis.

Estimated Time:3m 0s

Question 762Question →

A $62$ -year-old man comes to the clinic for a routine follow-up. Eight weeks ago, he was hospitalized for new-onset atrial fibrillation and was successfully converted to normal sinus rhythm. He was discharged on a regimen of amiodarone and apixaban. Today, the patient reports feeling well with no palpitations, shortness of breath, heat intolerance, weight changes, fatigue, or constipation. His pulse is $68$ /min and regular, and his blood pressure is $124/78$ mm Hg. Physical examination shows a normal-sized, non-tender thyroid gland with no palpable nodules. There is no resting tremor.

Laboratory studies show the following:
Thyroid-stimulating hormone (TSH): $7.8$ $\mu$ U/mL (Normal: $0.5-5.0$ $\mu$ U/mL)
Free thyroxine (T4): $2.1$ ng/dL (Normal: $0.9-1.7$ ng/dL)
Free triiodothyronine (T3): $1.6$ pg/mL (Normal: $2.3-4.1$ pg/mL)

Which of the following is the most appropriate next step in the management of this patient's thyroid function?

Continue current management and repeat thyroid function tests in 12 weeks

Discontinue amiodarone and switch to an alternative antiarrhythmic agent

Initiate therapy with low-dose levothyroxine

Initiate therapy with methimazole

Perform a radioactive iodine uptake scan

Show answer & explanation

Answer: Continue current management and repeat thyroid function tests in 12 weeks

Answer

Continue current management and repeat thyroid function tests in 12 weeks

The correct answer is to continue current management and observe. Amiodarone is an iodine-rich antiarrhythmic drug that exerts multiple physiological effects on the thyroid axis. One of its primary effects is the inhibition of 5'-deiodinase, the enzyme responsible for the peripheral conversion of thyroxine (T4) to the more active triiodothyronine (T3). This inhibition results in an elevation of serum free T4 and a reduction in serum free T3. Because T3 is the primary hormone providing negative feedback to the hypothalamus and pituitary, the transient drop in T3 leads to a compensatory increase in thyroid-stimulating hormone (TSH). This classic physiological profile (mildly elevated TSH, elevated free T4, and low-normal or low free T3) typically peaks within the first 1 to 3 months of amiodarone therapy. Since the patient is entirely asymptomatic and euthyroid, this pattern does not represent true hypothyroidism or thyrotoxicosis. No medical intervention is required, and the TSH will typically normalize over the next 3 to 6 months as a new steady state is achieved.

Step-by-Step Solution

1

Analyze the patient's symptoms and vital signs in the context of his recent medication changes.

The patient is completely asymptomatic, has normal vital signs, and was started on amiodarone 8 weeks ago.

Establishing the clinical status (euthyroid) is crucial before interpreting laboratory abnormalities.

2

Interpret the thyroid function test profile.

The labs show a mildly elevated TSH, an elevated free T4, and a low free T3.

Identifying the specific pattern of hormone alterations helps differentiate between true thyroid disease and medication effects.

3

Correlate the lab profile with the physiological effects of amiodarone.

The pattern matches the expected 5'-deiodinase inhibition caused by amiodarone early in therapy.

Amiodarone predictably decreases peripheral T4 to T3 conversion, leading to transient TSH elevation due to reduced T3-mediated negative feedback.

4

Determine the appropriate clinical intervention.

Observation and repeat testing is selected.

Because these changes are physiologic and the patient is euthyroid, no active medical intervention or drug discontinuation is required.

Key Concept

Early physiologic thyroid function alterations secondary to amiodarone therapy

Estimated Time:1m 30s

Question 763Question →

A $28$ -year-old man comes to the clinic with a $5$ -day history of right knee pain and swelling, accompanied by bilateral eye redness and a burning sensation during urination. He has a medical history of major depressive disorder, for which he takes daily fluoxetine. Four weeks ago, he traveled to Southeast Asia and experienced a self-limited episode of severe watery diarrhea. His temperature is $37.6^\circ\text{C}$ ( $99.7^\circ\text{F}$ ), blood pressure is $122/78\text{ mm Hg}$ , and pulse is $88/\text{min}$ . Physical examination shows bilateral conjunctival injection with no purulent discharge. The right knee is markedly swollen, warm, and tender to palpation. There is also tenderness over the posterior aspect of the left heel. Arthrocentesis of the right knee yields yellow, translucent synovial fluid with a leukocyte count of $15,000/\text{mm}^3$ ( $50\%$ neutrophils). Gram stain and cultures of the synovial fluid are negative. Polarized light microscopy reveals no crystals.

Laboratory studies show:
Leukocyte count: $11,500/\text{mm}^3$
Hemoglobin: $13.8\text{ g/dL}$
Thyroid-stimulating hormone (TSH): $0.3\text{ \mu U/mL}$ (N: $0.5$ – $5.0\text{ \mu U/mL}$ )
Free T4: $0.7\text{ ng/dL}$ (N: $0.9$ – $1.7\text{ ng/dL}$ )

Which of the following is the most appropriate next step in management?

Oral naproxen

Intravenous ceftriaxone and vancomycin

Oral tramadol

Oral levothyroxine

Direct notification of the patient's recent sexual partners

Show answer & explanation

Answer: Oral naproxen

Answer

Oral naproxen

The correct answer is oral naproxen. This patient's presentation of asymmetric oligoarthritis (knee), enthesitis (Achilles tendinopathy), bilateral conjunctivitis, and urethritis following a severe diarrheal illness is highly characteristic of reactive arthritis. Reactive arthritis is an autoimmune seronegative spondyloarthropathy that develops weeks after an enteric infection (e.g., Campylobacter, Salmonella, Shigella) or a genitourinary infection (e.g., Chlamydia trachomatis). The synovial fluid is inflammatory (typically between 2,000 and 50,000 leukocytes/mm³) but sterile, which is confirmed by the negative Gram stain and culture. First-line therapy for the acute symptomatic management of the arthritis and enthesitis is nonsteroidal anti-inflammatory drugs (NSAIDs), such as naproxen, ibuprofen, or indomethacin.

Step-by-Step Solution

1

Analyze the classic triad of symptoms and the preceding history.

The patient has acute asymmetric oligoarthritis, conjunctivitis, and urethritis occurring 4 weeks after an episode of traveler's diarrhea.

This constellation of symptoms strongly points to reactive arthritis, a seronegative spondyloarthropathy often triggered by enteric infections (e.g., Salmonella, Campylobacter).

2

Evaluate the synovial fluid analysis.

The synovial fluid leukocyte count is 15,000/mm³ with a negative Gram stain and culture.

This confirms an inflammatory etiology (typically 2,000 to 50,000 WBCs/mm³) but rules out an active infectious process (septic arthritis), confirming that the arthritis is a sterile, immune-mediated reaction.

3

Determine the first-line pharmacologic treatment for this condition while considering the patient's current medications.

Nonsteroidal anti-inflammatory drugs (NSAIDs) such as naproxen are indicated.

NSAIDs are the cornerstone of initial therapy for reactive arthritis. Other pain management options like tramadol must be avoided due to the patient's concurrent fluoxetine use.

Key Concept

Reactive arthritis classically presents with a triad of nongonococcal urethritis, asymmetric oligoarthritis, and conjunctivitis following a gastrointestinal or genitourinary infection. The initial treatment of choice is nonsteroidal anti-inflammatory drugs (NSAIDs).

Question 764Question →

Routine rounding in the normal newborn nursery involves the examination of a 48-hour-old full-term neonate. The pregnancy was uncomplicated, and maternal group B Streptococcus screening was negative. The neonate is feeding well and has not had any documented fevers. However, the parents are highly anxious about a new, widespread skin eruption that appeared earlier this morning. Physical examination reveals multiple 2- to 3-mm pale yellow pustules surrounded by a prominent erythematous base, distributed over the chest, abdomen, and proximal extremities. The palms and soles are completely spared. Vital signs, including temperature, are within normal physiological limits for age. Which of the following is the most appropriate next step in the management of this patient?

Initiation of intravenous ampicillin and gentamicin

Intravenous acyclovir and viral PCR testing

Gram stain and bacterial culture of the pustule fluid

Reassurance and continued routine care

Application of topical mupirocin to the affected areas

Show answer & explanation

Answer: Reassurance and continued routine care

Answer

The most appropriate next step is reassurance and continued routine care, as the infant has erythema toxicum neonatorum.

The correct answer is reassurance and continued routine care. This neonate's presentation of 2- to 3-mm yellow pustules on a blotchy erythematous base that spares the palms and soles is the classic description of erythema toxicum neonatorum (ETN). ETN is a benign, self-limited condition that appears in up to half of all full-term neonates, typically within the first 24 to 72 hours of life. Because the infant is afebrile, feeding well, and has no signs of systemic illness, no diagnostic testing or pharmacotherapy is required. The appropriate management is clinical observation and reassuring the anxious parents.

Step-by-Step Solution

1

Analyze the clinical presentation and physical exam findings.

The neonate has asymptomatic yellow pustules on an erythematous base, sparing the palms and soles, and is otherwise well-appearing, afebrile, and feeding normally.

Identifying the specific characteristics of the rash and the overall clinical status is essential to differentiate benign newborn rashes from infectious emergencies.

2

Formulate a diagnosis based on the rash morphology and timing.

The findings are pathognomonic for erythema toxicum neonatorum.

Erythema toxicum neonatorum typically presents in the first few days of life with a 'flea-bitten' appearance (pustules on an erythematous base) and classically spares the palms and soles.

3

Determine the appropriate management for the diagnosed condition.

Observation and parental reassurance are indicated.

Because erythema toxicum neonatorum is a benign, self-resolving condition, unnecessary testing or pharmacological intervention should be avoided.

Key Concept

Erythema toxicum neonatorum is a benign, self-limited rash in neonates characterized by erythematous macules and pustules that spare the palms and soles, requiring only clinical diagnosis and reassurance.

Question 765Question →

Match each clinical presentation in a patient with advanced HIV infection to the most likely central nervous system etiology.

Click a left item, then click its matching right item

Show answer & explanation

Answer

The correct pairings match each clinical vignette to its corresponding HIV-associated central nervous system complication based on CD4 count thresholds, distinct neuroimaging characteristics, and cerebrospinal fluid findings.

Each diagnosis represents a distinct opportunistic condition in advanced HIV, distinguishable by unique neuroimaging patterns (enhancing vs. non-enhancing, solitary vs. multiple, mass effect vs. no mass effect), focal versus global neurologic symptoms, and specific cerebrospinal fluid analysis findings.

Step-by-Step Solution

1

Analyze the first clinical vignette focusing on CD4 count (< 100 cells/mm³), symptoms (seizures, focal deficits), and MRI findings (multiple ring-enhancing lesions in basal ganglia).

Identified as Toxoplasma gondii encephalitis.

This is the most common cause of focal brain lesions in patients with AIDS, characterized classically by multiple enhancing lesions in the deep white matter and basal ganglia.

2

Analyze the second vignette focusing on the solitary, large periventricular mass and positive CSF Epstein-Barr virus PCR.

Identified as Primary central nervous system lymphoma.

Primary CNS lymphoma in HIV is an AIDS-defining malignancy heavily associated with EBV, presenting typically as a solitary, weakly enhancing periventricular mass.

3

Evaluate the third vignette noting the lack of mass effect, non-enhancing asymmetric white matter lesions, and subacute focal deficits.

Identified as Progressive multifocal leukoencephalopathy.

PML is a demyelinating disease caused by JC virus reactivation, classically appearing on MRI as patchy, non-enhancing white matter lesions without edema or mass effect.

4

Review the fourth vignette recognizing the high CSF opening pressure and presence of encapsulated budding yeast.

Identified as Cryptococcal meningitis.

Cryptococcal neoformans characteristically causes severe meningoencephalitis with highly elevated opening pressures; encapsulated budding yeast is pathognomonic on India ink or histopathology.

5

Assess the final vignette identifying the gradual cognitive decline combined with symmetric atrophy and white matter changes.

Identified as HIV-associated neurocognitive disorder.

HAND (including HIV dementia) presents with progressive cognitive and motor decline; MRI reflects generalized brain volume loss and diffuse, symmetric white matter signal abnormalities without focal lesions.

Key Concept

Differential diagnosis of central nervous system lesions and infections in patients with advanced HIV, utilizing neuroimaging, CD4 count, and CSF analysis.

Estimated Time:2m 0s

Question 766Question →

Match each clinical presentation of a zoonotic or vector-borne infectious disease with the most appropriate targeted antimicrobial therapy.

Click a left item, then click its matching right item

Show answer & explanation

Answer

The correct matches align specific zoonotic and vector-borne clinical syndromes with their definitive antimicrobial therapies: Babesiosis is treated with atovaquone and azithromycin; cat scratch disease with azithromycin; Chagas disease with benznidazole; tularemia with streptomycin; and Q fever with doxycycline.

Each pathogen requires a specific class of antimicrobial based on its unique biology: Babesia (protozoan) requires atovaquone/azithromycin; Bartonella (fastidious bacteria) responds to azithromycin; Trypanosoma (parasite) requires benznidazole; Francisella (Gram-negative coccobacillus) is best treated with aminoglycosides; and Coxiella (intracellular bacteria) requires tetracyclines.

Step-by-Step Solution

1

Identify the etiology for each distinct clinical vignette based on exposure history and physical or laboratory findings.

The vignettes describe Babesiosis, cat scratch disease, Chagas disease, tularemia, and Q fever, respectively.

Accurate pathogen identification is the prerequisite for selecting targeted antimicrobial therapy.

2

Determine the therapy for Babesiosis (hemolytic anemia, intraerythrocytic tetrads).

Match with atovaquone and azithromycin.

This combination effectively targets the intraerythrocytic protozoa while minimizing toxicity.

3

Determine the therapy for cat scratch disease (kitten exposure, regional lymphadenitis).

Match with azithromycin.

A short course of azithromycin accelerates the resolution of Bartonella henselae lymphadenopathy.

4

Determine the therapy for acute Chagas disease (South American travel, Romaña sign).

Match with benznidazole.

Benznidazole (or nifurtimox) is the required therapy for acute Trypanosoma cruzi infection.

5

Determine the therapy for tularemia (rabbit exposure, ulceroglandular disease).

Match with streptomycin.

Aminoglycosides are the gold standard for severe or ulceroglandular Francisella tularensis infection.

6

Determine the therapy for acute Q fever (livestock exposure, atypical pneumonia/hepatitis).

Match with doxycycline.

Doxycycline effectively clears the intracellular pathogen Coxiella burnetii.

Key Concept

Targeted antimicrobial therapy for zoonotic and vector-borne infectious diseases must be selected based on distinct epidemiological exposures and classic clinical manifestations.

Estimated Time:1m 30s

Question 767Question →

A 32-year-old G3P3 woman experiences severe vaginal bleeding immediately following the vaginal delivery of a 4,300 g neonate. Her pulse is 122/min, and blood pressure is 85/50 mm Hg. Abdominal examination reveals a soft, poorly contracted uterus palpated above the umbilicus. Two large-bore intravenous lines are placed, and fluid resuscitation is initiated.

Arrange the following management steps for this patient's condition in the correct sequential order, from the most appropriate initial intervention to the definitive final procedure for refractory hemorrhage.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequential management of postpartum hemorrhage due to uterine atony progresses from basic mechanical and primary pharmacological measures, to secondary uterotonics, minimally invasive mechanical tamponade, uterus-conserving surgery, and ultimately definitive hysterectomy.

The management of postpartum hemorrhage from uterine atony requires a rapid, stepwise escalation. Initial steps involve bimanual massage and primary uterotonics (oxytocin). If unsuccessful, secondary uterotonics (carboprost, methylergonovine) are utilized. Continued hemorrhage warrants intrauterine balloon tamponade, followed by surgical interventions such as uterine compression sutures, with peripartum hysterectomy reserved as the definitive, life-saving measure of last resort.

Step-by-Step Solution

1

Evaluate the clinical presentation and identify the etiology of hemorrhage.

The patient has a soft, boggy uterus after delivering a macrosomic infant, diagnostic of postpartum hemorrhage due to uterine atony.

Accurate identification of the etiology directs the specific stepwise management algorithm.

2

Determine the first-line intervention.

Bimanual uterine massage and primary uterotonics (oxytocin) are prioritized.

These are the most rapid and effective initial treatments to promote uterine contraction.

3

Identify subsequent medical options if first-line therapy fails.

Secondary uterotonics such as carboprost, methylergonovine, or misoprostol are administered.

Escalating pharmacological therapy is indicated before moving to invasive mechanical procedures.

4

Establish the sequence of procedural and surgical interventions for refractory cases.

Intrauterine balloon tamponade, followed by uterine compression sutures, and finally hysterectomy.

Interventions must progress systematically from the least invasive (tamponade) to uterus-conserving surgery (sutures), and ultimately to definitive life-saving surgery (hysterectomy) to minimize morbidity while preventing exsanguination.

Key Concept

The sequential, stepwise management algorithm for postpartum hemorrhage due to uterine atony.

Question 768Question →

A medical student on a psychiatry clerkship is reviewing the adverse effect profiles of commonly prescribed psychiatric medications. Match each of the following psychotropic medications to the clinical vignette that best describes its characteristic adverse effect or toxicity.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Clozapine matches with agranulocytosis; Lamotrigine matches with Stevens-Johnson syndrome; Lithium matches with toxicity exacerbated by thiazides; Bupropion matches with seizures in eating disorders; Ziprasidone matches with QTc prolongation.

Each psychotropic medication has a unique, high-yield adverse effect profile that must be recognized to ensure patient safety. Clozapine requires strict ANC monitoring due to agranulocytosis risk. Lamotrigine must be titrated slowly to prevent Stevens-Johnson syndrome. Lithium has a narrow therapeutic window, and toxicity is easily precipitated by volume depletion or thiazides. Bupropion lowers the seizure threshold and is contraindicated in eating disorders. Ziprasidone is strongly associated with QTc prolongation.

Step-by-Step Solution

1

Analyze the side effect profile for Clozapine.

Identify that Clozapine can cause life-threatening agranulocytosis, presenting with fever, sore throat, and low ANC.

This is a mandatory safety parameter monitored via the REMS program.

2

Analyze the side effect profile for Lamotrigine.

Identify that Lamotrigine can cause Stevens-Johnson syndrome, a severe blistering mucosal rash, especially with fast titration.

Understanding titration protocols is essential to prevent this dermatologic emergency.

3

Analyze the side effect profile for Lithium.

Identify that Lithium causes nephrogenic diabetes insipidus and has a narrow therapeutic index; toxicity (ataxia, tremor) is worsened by thiazide diuretics.

Drug-drug interactions are critical in managing patients on mood stabilizers.

4

Analyze the side effect profile for Bupropion.

Identify that Bupropion lowers the seizure threshold, making it contraindicated in bulimia nervosa due to electrolyte imbalances.

Matching contraindications with patient history ensures safe prescribing.

5

Analyze the side effect profile for Ziprasidone.

Identify that Ziprasidone is associated with significant QTc prolongation.

ECG monitoring may be required to prevent arrhythmias like torsades de pointes.

Key Concept

Psychotropic Medication Adverse Effects

Question 769Question →

Match each clinical presentation of pneumonia or febrile respiratory illness to its most likely causative pathogen based on the provided epidemiological clues and distinct clinical findings.

Click a left item, then click its matching right item

Show answer & explanation

Answer

The scenarios match to: Alcohol dependence -> Klebsiella pneumoniae; Cooling tower -> Legionella pneumophila; Dormitory resident with targetoid rash -> Mycoplasma pneumoniae; Bird handler -> Chlamydia psittaci; Livestock worker -> Coxiella burnetii.

The correct pairings align each distinct clinical syndrome and epidemiological exposure with its classic respiratory pathogen. Identifying these unique risk factors—such as avian exposure for psittacosis, contaminated water aerosols for Legionnaires' disease, and livestock exposure for Q fever—is crucial because these organisms dictate specific antimicrobial management that differs from typical community-acquired pneumonia pathways.

Step-by-Step Solution

1

Identify the unique epidemiological risk factor in each patient's history.

Identified exposures: alcohol dependence (aspiration risk), cooling tower (aerosolized water), dormitory (close quarters), bird handling (avian zoonosis), and livestock farm (ruminant zoonosis).

Epidemiological exposures are the primary diagnostic clues for differentiating atypical and specific bacterial pneumonias.

2

Correlate the distinct systemic clinical findings with known pathogen profiles.

Linked thick hemoptysis to lobar necrosis, hyponatremia/diarrhea to systemic infection, targetoid rash to erythema multiforme, and hepatitis without rash to specific zoonoses.

Many of these pathogens present with classic extrapulmonary manifestations that confirm the diagnosis alongside the pulmonary findings.

3

Pair each synthesized clinical and epidemiological profile with the correct pathogen.

The final pairings correctly align the historical and clinical clues to Klebsiella, Legionella, Mycoplasma, C. psittaci, and C. burnetii.

Accurate pathogen identification guides the selection of targeted antimicrobial therapy, such as adding a macrolide or fluoroquinolone for atypical coverage.

Key Concept

Clinical and epidemiological differentiation of atypical and specific lobar pneumonias to guide targeted antimicrobial therapy.

Estimated Time:1m 30s

Question 770Question →

During morning rounds in the intensive care unit, the medical team evaluates a patient recovering from a catheter-associated bloodstream infection. Empiric therapy with intravenous vancomycin and cefepime was initiated three days ago for suspected sepsis. The patient is currently afebrile and hemodynamically stable, and the offending central venous catheter has been removed. Final blood culture results from admission now reveal growth of *Enterococcus faecalis* in two out of two sets. The isolate demonstrates susceptibility to ampicillin, vancomycin, linezolid, and daptomycin. Which of the following is the most appropriate modification to this patient's antimicrobial regimen?

Discontinue cefepime and continue intravenous vancomycin

Discontinue vancomycin and continue intravenous cefepime

Continue the current regimen of intravenous vancomycin and cefepime

Discontinue vancomycin and cefepime, and initiate intravenous ampicillin

Discontinue vancomycin and cefepime, and initiate intravenous daptomycin

Show answer & explanation

Answer: Discontinue vancomycin and cefepime, and initiate intravenous ampicillin

Answer

Discontinue vancomycin and cefepime, and initiate intravenous ampicillin

The correct approach is to discontinue the broad-spectrum empiric regimen and initiate intravenous ampicillin. For *Enterococcus faecalis* infections that are susceptible to ampicillin, beta-lactam therapy (such as ampicillin or penicillin) is the treatment of choice. Ampicillin is preferred over vancomycin because it is highly active, bactericidal, has a narrower spectrum of activity, and helps prevent the development of vancomycin-resistant enterococci (VRE). De-escalating therapy once culture and susceptibility data are available is a core principle of antibiotic stewardship.

Step-by-Step Solution

1

Identify the pathogen and its susceptibility profile from the blood culture results.

The pathogen is *Enterococcus faecalis*, which is susceptible to ampicillin, vancomycin, linezolid, and daptomycin.

Correct identification and susceptibility testing are required to transition from empiric to targeted therapy.

2

Determine the optimal targeted therapy for susceptible *Enterococcus*.

Ampicillin is the drug of choice for susceptible *Enterococcus faecalis* due to its bactericidal activity and narrow spectrum.

Beta-lactams are preferred over vancomycin for susceptible isolates to ensure optimal efficacy and minimize resistance.

3

Apply principles of antimicrobial stewardship to the current regimen.

The overly broad empiric agents (vancomycin and cefepime) should be discontinued, and targeted therapy with intravenous ampicillin should be initiated.

De-escalating therapy reduces the risk of adverse effects, lowers costs, and prevents the emergence of multidrug-resistant organisms.

Key Concept

Antimicrobial Stewardship and Enterococcal Bacteremia Management

Question 771Question →

An outpatient evaluation is conducted for a $35$ -year-old female patient who reports severe fatigue and feeling constantly cold. Over the past $6$ months, she has noticed a $5\text{-kg}$ ( $11\text{-lb}$ ) weight gain despite a poor appetite, and her menstrual cycles have completely stopped. She has no chronic medical conditions and takes no medications. Vital signs show a temperature of $36.2^\circ\text{C}$ ( $97.2^\circ\text{F}$ ), blood pressure of $108/68 \text{ mm Hg}$ , and pulse of $52/\text{min}$ . Physical examination reveals dry skin, delayed relaxation of the deep tendon reflexes, and no palpable thyroid enlargement. Visual fields are full to confrontation. Laboratory results are as follows:

Thyroid-stimulating hormone (TSH): $0.1 \text{ mU/L}$ (Normal: $0.4 - 4.0 \text{ mU/L}$ )
Free thyroxine (T4): $0.4 \text{ ng/dL}$ (Normal: $0.9 - 1.7 \text{ ng/dL}$ )

Which of the following is the most likely underlying cause of this patient's clinical presentation?

Anterior pituitary adenoma

Autoimmune destruction of the thyroid gland

Surreptitious use of levothyroxine

Decreased peripheral conversion of thyroxine

Granulomatous inflammation of the thyroid gland

Show answer & explanation

Answer: Anterior pituitary adenoma

Answer

The most likely diagnosis is an anterior pituitary adenoma, which causes secondary hypothyroidism and hypogonadotropic hypogonadism.

The correct answer accurately synthesizes the laboratory data (low free T4 and low TSH) to localize the defect to the central nervous system (pituitary or hypothalamus) rather than the thyroid gland itself. The concurrent history of amenorrhea makes an anterior pituitary adenoma the most likely unifying diagnosis, as expanding pituitary lesions frequently compress adjacent normal pituitary tissue, leading to multiple anterior pituitary hormone deficiencies (panhypopituitarism).

Step-by-Step Solution

1

Interpret the clinical symptoms and vital signs.

The patient exhibits weight gain, fatigue, cold intolerance, delayed reflexes, and bradycardia, establishing a clinical hypothyroid state.

Initial pattern recognition of the metabolic state directs further laboratory analysis.

2

Analyze the thyroid function laboratory tests.

The free T4 is low, confirming hypothyroidism, while the TSH is inappropriately low. This combination rules out a primary thyroid gland defect and indicates central (secondary) hypothyroidism.

The relationship between TSH and T4 determines the anatomical location of the defect in the hypothalamic-pituitary-thyroid axis.

3

Correlate the laboratory diagnosis with the secondary symptom of amenorrhea.

The combination of central hypothyroidism and amenorrhea points to a widespread disruption of the anterior pituitary gland.

A pituitary adenoma can cause a mass effect or hyperprolactinemia, which simultaneously disrupts the secretion of both TSH and gonadotropins (FSH/LH).

Key Concept

Secondary (central) hypothyroidism is characterized by a low free T4 and a low or inappropriately normal TSH. When accompanied by other pituitary hormone deficiencies (such as amenorrhea), it strongly suggests a pituitary lesion like an adenoma.

Estimated Time:50s

Question 772Question →

A 32-year-old woman is evaluated in the clinic for progressive generalized muscle weakness and fatigue over the past three weeks. She has a past medical history of two episodes of nephrolithiasis in the last three years but takes no daily medications. She reports no recent history of diarrhea, vomiting, or dietary changes. Her temperature is $37.0°\text{C}$ ( $98.6°\text{F}$ ), blood pressure is $112/72 \text{ mm Hg}$ , pulse is $82/\text{min}$ , and respiratory rate is $18/\text{min}$ . Physical examination reveals decreased deep tendon reflexes globally but is otherwise unremarkable.

Laboratory results are as follows:

Test	Result	Reference Range
Sodium ( $Na^+$ )	$140 \text{ mEq/L}$	$136-145 \text{ mEq/L}$
Potassium ( $K^+$ )	$2.7 \text{ mEq/L}$	$3.5-5.0 \text{ mEq/L}$
Chloride ( $Cl^-$ )	$116 \text{ mEq/L}$	$95-105 \text{ mEq/L}$
Bicarbonate ( $HCO_3^-$ )	$14 \text{ mEq/L}$	$22-28 \text{ mEq/L}$
Blood urea nitrogen	$12 \text{ mg/dL}$	$7-18 \text{ mg/dL}$
Creatinine	$0.9 \text{ mg/dL}$	$0.6-1.2 \text{ mg/dL}$

Arterial blood gas (room air):

Test	Result	Reference Range
pH	$7.27$	$7.35-7.45$
$PaCO_2$	$29 \text{ mm Hg}$	$35-45 \text{ mm Hg}$
$PaO_2$	$96 \text{ mm Hg}$	$75-105 \text{ mm Hg}$

Urinalysis reveals a pH of 6.5, specific gravity of 1.015, and is negative for protein, blood, and glucose.

Based on the clinical presentation and laboratory findings, which of the following best describes this patient's underlying condition and acid-base status?

Normal anion gap metabolic acidosis with appropriate respiratory compensation due to a distal tubular defect

High anion gap metabolic acidosis with appropriate respiratory compensation due to unmeasured endogenous acids

Mixed normal anion gap metabolic acidosis and primary respiratory alkalosis due to a proximal tubular defect

Mixed normal anion gap metabolic acidosis and primary respiratory acidosis due to gastrointestinal bicarbonate loss

Normal anion gap metabolic acidosis with inadequate respiratory compensation due to reduced adrenal aldosterone secretion

Show answer & explanation

Answer: Normal anion gap metabolic acidosis with appropriate respiratory compensation due to a distal tubular defect

Answer

Normal anion gap metabolic acidosis with appropriate respiratory compensation due to a distal tubular defect

The patient's laboratory results demonstrate a normal anion gap metabolic acidosis (NAGMA) with appropriate respiratory compensation, secondary to Type 1 (distal) renal tubular acidosis (RTA). A step-wise evaluation reveals acidemia (pH 7.27) with a low bicarbonate (

14 \text{ mEq/L}

), signifying metabolic acidosis. The anion gap is normal at

10 \text{ mEq/L}

. Using Winter's formula, the expected

PaCO_2

is calculated as

1.5 \times 14 + 8 = 29 \pm 2 \text{ mm Hg}

. Because the actual

PaCO_2

is exactly

29 \text{ mm Hg}

, the respiratory compensation is fully appropriate, meaning there is no mixed acid-base disorder. The underlying etiology is a distal tubular defect (Type 1 RTA), which is clinically characterized by severe hypokalemia, the inability to acidify urine below a pH of 5.5 (patient's urine pH is 6.5), and a high risk of calcium phosphate kidney stones forming in the alkaline urine.

Step-by-Step Solution

1

Identify the primary acid-base disturbance by evaluating the arterial pH and serum bicarbonate.

The low pH (

7.27

) and low serum bicarbonate (

14 \text{ mEq/L}

) confirm a primary metabolic acidosis.

Establishing the primary disturbance directs the subsequent steps of the diagnostic algorithm.

2

Calculate the serum anion gap (AG) to classify the etiology of the metabolic acidosis.

The calculated AG is

[Na^+] - ([Cl^-] + [HCO_3^-]) = 140 - (116 + 14) = 10 \text{ mEq/L}

, which falls within the normal range (

10-14 \text{ mEq/L}

).

Differentiating between a normal and high anion gap significantly narrows the differential diagnosis.

3

Apply Winter's formula to determine if the respiratory compensation is appropriate or if a mixed disorder is present.

Expected

PaCO_2 = 1.5 \times [HCO_3^-] + 8 \pm 2 = 1.5 \times 14 + 8 \pm 2 = 29 \pm 2 \text{ mm Hg}

. The patient's actual

PaCO_2

is

29 \text{ mm Hg}

, confirming perfect respiratory compensation with no secondary respiratory disorder.

Failure to accurately calculate the expected compensatory response frequently leads to the misdiagnosis of a mixed acid-base disorder.

4

Determine the specific cause of the normal anion gap metabolic acidosis based on clinical history, serum potassium, and urine pH.

The presence of severe hypokalemia (

2.7 \text{ mEq/L}

), an inappropriately alkaline urine (pH

6.5

) despite systemic acidemia, and a history of nephrolithiasis strongly point to Type 1 (distal) renal tubular acidosis.

These findings reflect the specific pathophysiological defect of impaired distal tubular hydrogen ion secretion, which inherently prevents proper urine acidification and predisposes to calcium phosphate stone formation.

Key Concept

Type 1 (distal) renal tubular acidosis presents as a normal anion gap metabolic acidosis with hypokalemia, an inappropriately alkaline urine (pH > 5.5) despite systemic acidemia, and a strong predisposition to calcium phosphate nephrolithiasis.

Estimated Time:1m 30s

Question 773Question →

A 34-year-old G4P3 patient at 37 weeks of gestation is brought to the emergency department by her husband due to sudden-onset, severe, and continuous lower abdominal pain accompanied by dark red vaginal bleeding. Her previous pregnancies were delivered vaginally at term without complications. She has a history of chronic hypertension. Her current blood pressure is 165/100 mm Hg, pulse is 115/min, and respirations are 20/min. Physical examination reveals a rigid, hypertonic, and diffusely tender uterus. Speculum examination confirms a moderate amount of dark blood in the vaginal vault with no active cervical lesions. The cervix is 2 cm dilated and 50% effaced. Fetal heart rate monitoring demonstrates a baseline of 90/min, minimal variability, and recurrent late decelerations. Which of the following is the most appropriate next step in management?

Immediate cesarean delivery

Administration of intravenous terbutaline

Expectant management with continuous fetal monitoring

Reassurance for normal physiologic bloody show

Comprehensive transabdominal ultrasonography

Show answer & explanation

Answer: Immediate cesarean delivery

Answer

Immediate cesarean delivery is the required intervention for a severe placental abruption accompanied by acute fetal compromise.

The correct approach is emergent surgical delivery. This patient's presentation of sudden-onset, severe abdominal pain, dark vaginal bleeding, and a rigid, hypertonic uterus is classic for placental abruption (premature separation of the placenta). The fetal heart rate tracing shows profound bradycardia, minimal variability, and late decelerations, all of which signify severe uteroplacental insufficiency and acute fetal compromise. When placental abruption is accompanied by a non-reassuring fetal status and the patient is not in advanced labor (cervix only 2 cm dilated), immediate cesarean delivery is mandated to prevent fetal demise and severe maternal complications like hemorrhage and DIC.

Step-by-Step Solution

1

Evaluate maternal and fetal stability based on vital signs and monitoring.

The mother is hypertensive and tachycardic. The fetal heart rate tracing shows bradycardia (90/min) with minimal variability and late decelerations, indicating severe hypoxia and distress.

Establishing stability dictates the urgency of the intervention.

2

Identify the underlying obstetric complication.

The classic triad of sudden continuous abdominal pain, a rigid/hypertonic uterus, and dark vaginal bleeding in a hypertensive patient strongly points to placental abruption.

Accurate diagnosis is necessary to select the correct management pathway.

3

Determine the definitive next step in management.

Because the fetus is in acute distress and vaginal delivery is not imminent (cervix is only 2 cm dilated), immediate cesarean delivery is required.

Expeditious delivery prevents fetal demise and mitigates maternal risks such as disseminated intravascular coagulation (DIC).

Key Concept

Placental abruption presenting with a rigid, tender uterus and fetal distress necessitates emergent cesarean delivery.

Question 774Question →

A $38$ -year-old man is brought to the emergency department due to a severe nosebleed that has not stopped for $2$ hours, along with bleeding gums and profound fatigue over the past week. His temperature is $37.8^\circ\text{C}$ ( $100.0^\circ\text{F}$ ), blood pressure is $110/70$ mm Hg, and heart rate is $112$ /min. Physical examination reveals diffuse petechiae across his chest and large ecchymoses on his extremities. Laboratory studies show:

Complete Blood Count	Value
Hemoglobin	$8.2$ g/dL
Leukocyte count	$2,100/\text{mm}^3$
Platelet count	$18,000/\text{mm}^3$

Coagulation Profile	Value
Prothrombin time (PT)	$22$ seconds
Activated partial thromboplastin time (aPTT)	$55$ seconds
Fibrinogen	$75$ mg/dL
D-dimer	$>10,000$ ng/mL

A peripheral blood smear reveals pancytopenia and several large, atypical promyelocytes containing multiple needle-like intracytoplasmic inclusions.

Arrange the following steps in the most appropriate chronological order for the optimal management of this patient's condition.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence is: 1) Empirical administration of all-trans retinoic acid (ATRA), 2) Bone marrow aspiration and biopsy, 3) Molecular confirmation of the PML::RARA fusion gene, 4) Addition of arsenic trioxide (ATO) to the treatment regimen.

Acute promyelocytic leukemia (APL) is a medical emergency that presents with pancytopenia and severe coagulopathy (DIC), driven by the release of procoagulants from leukemic promyelocytes. The first and most critical step is the empirical administration of all-trans retinoic acid (ATRA). ATRA induces differentiation of the malignant promyelocytes into mature neutrophils, which rapidly halts the coagulopathy and prevents fatal bleeding. Because of the high risk of early mortality from hemorrhage, ATRA must be given as soon as APL is suspected based on peripheral smear morphology (e.g., atypical promyelocytes with Auer rods), without waiting for definitive diagnostic tests. After ATRA is initiated and supportive care (e.g., cryoprecipitate, platelets) is provided, a bone marrow aspiration and biopsy is performed. The obtained marrow sample is then used for molecular confirmation via FISH or PCR to identify the pathognomonic t(15;17) translocation (PML::RARA fusion gene). Once the diagnosis is definitively confirmed and the patient's risk profile is established, arsenic trioxide (ATO) and/or chemotherapy is added to ATRA to complete the definitive induction treatment regimen.

Step-by-Step Solution

1

Recognize the clinical presentation of Acute Promyelocytic Leukemia (APL).

The patient has pancytopenia, bleeding, DIC (low fibrinogen, elevated PT/aPTT/D-dimer), and atypical promyelocytes with Auer rods (needle-like inclusions).

Identifying APL is critical because it is a hematologic emergency requiring immediate specific intervention.

2

Determine the immediate next step in management.

Empirical initiation of ATRA is required as the very first step.

ATRA promotes differentiation of the leukemic promyelocytes, rapidly reversing the severe coagulopathy and preventing fatal hemorrhage. It must not be delayed for confirmatory testing.

3

Identify the proper sequence of diagnostic confirmation.

Bone marrow biopsy is performed to obtain the necessary sample, followed by molecular testing (FISH/PCR) on that sample.

Definitive diagnosis requires identifying the t(15;17) translocation, but the tissue must first be safely collected via biopsy.

4

Determine the definitive treatment step.

Add ATO (and sometimes anthracyclines, depending on risk stratification) to complete the induction regimen.

Once the diagnosis is genetically confirmed and risk is stratified, standard definitive induction therapy is implemented.

Key Concept

In patients with suspected acute promyelocytic leukemia (APL), all-trans retinoic acid (ATRA) must be initiated immediately to prevent fatal hemorrhage from disseminated intravascular coagulation (DIC), prior to obtaining a bone marrow biopsy and awaiting molecular confirmation.

Estimated Time:1m 30s

Question 775Question →

A 61-year-old man is evaluated in the surgical ward for new-onset right-sided back pain. He is currently on postoperative day $7$ following an open radical retropubic prostatectomy for localized prostate adenocarcinoma. His early postoperative recovery was routine, and he is tolerating a regular diet. Over the past $12$ hours, he has developed a fever and constant, dull pain in his right flank. He has a suprapubic catheter in place that is draining clear yellow urine. His temperature is $38.8^\circ\text{C}$ ( $101.8^\circ\text{F}$ ), blood pressure is $130/82$ mmHg, pulse is $105$ /min, and respiratory rate is $16$ /min. Physical examination demonstrates a soft, non-tender abdomen and a clean lower midline incision. There is pronounced right-sided costovertebral angle tenderness. Laboratory evaluation reveals a leukocyte count of $14,800/\text{mm}^3$ . Analysis of the urine from the suprapubic catheter is negative for leukocyte esterase and nitrites, and shows $1$ - $2$ leukocytes/hpf. Which of the following is the most appropriate next step in management?

CT scan of the abdomen and pelvis with intravenous contrast

Empiric intravenous administration of ceftriaxone

Duplex ultrasonography of the lower extremities

Chest radiography

Irrigation of the suprapubic catheter

Show answer & explanation

Answer: CT scan of the abdomen and pelvis with intravenous contrast

Answer

CT scan of the abdomen and pelvis with intravenous contrast

The correct response targets the need for definitive imaging of the genitourinary tract. The distal ureters are anatomically close to the prostate and bladder neck, making them highly susceptible to iatrogenic injury (such as ligation, kinking, or transection) during a radical prostatectomy. A unilateral ureteral ligation typically remains clinically silent for several days until the proximal hydronephrosis becomes severe enough to cause flank pain, capsular distension, and subsequent fever. The critical diagnostic clue in this vignette is the combination of costovertebral angle tenderness with a pristine urinalysis. Because the injured ureter is completely blocked, no inflammatory cells or bacteria from the affected side can reach the bladder. Therefore, treating empirically for pyelonephritis is incorrect. A CT scan of the abdomen and pelvis with intravenous contrast is the gold standard for diagnosis, as it can demonstrate unilateral hydroureteronephrosis, delayed nephrograms, or contrast extravasation if a leak is present.

Step-by-Step Solution

1

Analyze the timeline and localizing symptoms.

The patient has a fever and unilateral flank pain (CVA tenderness) on postoperative day 7 following a radical prostatectomy.

Identifying the 'W' (in this case, timeline points toward a deeper surgical complication or DVT, while the localizing sign points directly to the upper urinary tract).

2

Evaluate the laboratory findings in the context of the symptoms.

The urinalysis is completely normal despite symptoms suggestive of pyelonephritis.

A normal urinalysis in the presence of CVA tenderness and fever strongly suggests that the affected kidney is physically obstructed (e.g., ligated ureter), preventing abnormal urine/pus from reaching the bladder where the sample was collected.

3

Determine the highest-yield diagnostic test for the suspected surgical complication.

CT scan of the abdomen and pelvis with intravenous contrast is selected.

IV contrast is required to assess renal perfusion and, via delayed excretory phases, visualize the ureters to confirm mechanical obstruction (hydronephrosis) or extravasation of urine from an intraoperative ureteral injury.

Key Concept

Diagnosis and management of postoperative ureteral injury

Question 776Question →

Match each clinical trauma presentation with the most appropriate immediate diagnostic modality or therapeutic intervention.

Click a left item, then click its matching right item

Show answer & explanation

Answer

The presentations map to interventions based on hemodynamic stability and mechanism: hard signs of neck trauma require cervical intervention, unstable pelvic trauma without intraperitoneal fluid requires angiographic embolization or packing, unstable abdominal trauma with a positive FAST requires celiotomy, and stable blunt trauma requires cross-sectional imaging.

The correct pairings rely on core ATLS algorithms. Hard signs of penetrating neck trauma (stridor, expanding hematoma) require immediate operative exploration. In blunt trauma, hemodynamic stability dictates the pathway. Stable patients undergo CT scanning to diagnose specific injuries. Unstable patients undergo a FAST exam; a positive FAST leads to urgent celiotomy for intraperitoneal bleeding. If the FAST is negative in the setting of an unstable pelvic fracture, the bleeding is likely retroperitoneal, which is managed via angiographic embolization or preperitoneal packing.

Step-by-Step Solution

1

Evaluate the hemodynamic stability and airway status of each patient.

Patients 1, 2, and 3 have unstable vitals or impending airway compromise, whereas Patient 4 is hemodynamically stable.

Hemodynamic status is the primary branch point in trauma algorithms, determining if a patient can safely tolerate time-consuming imaging.

2

Identify the primary source or threat causing the instability.

Patient 1 has a cervical vascular/airway threat, Patient 2 has a retroperitoneal pelvic source, and Patient 3 has an intraperitoneal abdominal source.

The specific anatomical region of bleeding dictates the appropriate definitive intervention.

3

Select the guideline-concordant intervention for each presentation.

Unstable cervical trauma requires neck exploration. Unstable pelvic trauma without intraperitoneal fluid requires pelvic packing or angioembolization. Unstable abdominal trauma with positive FAST requires celiotomy. Stable abdominal trauma requires CT imaging.

Adhering to Advanced Trauma Life Support (ATLS) principles ensures rapid hemorrhage control and prevents avoidable trauma mortality.

Key Concept

Application of Advanced Trauma Life Support (ATLS) algorithms based on hemodynamic stability and specific injury patterns.

Question 777Question →

Match each clinical presentation occurring in the third trimester to the most likely obstetric or pregnancy-related diagnosis.

Click a left item, then click its matching right item

Show answer & explanation

Answer

The presentations successfully distinguish third-trimester hepatobiliary and hypertensive complications based on distinct laboratory and clinical hallmarks.

Each clinical vignette highlights the pathognomonic features of a specific obstetric complication. Hypoglycemia and hyperammonemia define Acute fatty liver of pregnancy; severe hypertension with thrombocytopenia and elevated AST points to HELLP syndrome; palmar and plantar pruritus is classic for Intrahepatic cholestasis of pregnancy; and isolated new-onset hypertension with proteinuria defines Preeclampsia without severe features.

Step-by-Step Solution

1

Analyze the first presentation involving right upper quadrant pain, profound hypoglycemia, and hyperammonemia.

This indicates fulminant hepatic synthetic failure, which matches Acute fatty liver of pregnancy.

Profound hypoglycemia and elevated ammonia are classic markers of liver synthetic dysfunction seen in AFLP, distinguishing it from other hepatic complications of pregnancy.

2

Evaluate the second presentation featuring severe hypertension, thrombocytopenia, and elevated AST.

This triad meets the diagnostic criteria for HELLP syndrome.

The combination of severe hypertension with specific laboratory abnormalities (low platelets and elevated transaminases) confirms HELLP syndrome.

3

Examine the third presentation detailing severe nocturnal pruritus of the palms and soles.

This presentation is the pathognomonic symptom of Intrahepatic cholestasis of pregnancy.

Pruritus without a primary rash that predominantly affects the palms and soles is the classic hallmark of ICP, driven by elevated serum bile acids.

4

Review the fourth presentation showing asymptomatic mild-to-moderate hypertension and 320 mg of proteinuria.

These findings fulfill the criteria for Preeclampsia without severe features.

Blood pressure >= 140/90 mm Hg and >= 300 mg proteinuria/day after 20 weeks gestation without end-organ damage or severe symptoms define this condition.

Key Concept

Differentiating obstetric complications involving the liver and hypertensive disorders of pregnancy.

Question 778Question →

An endocrinologist is reviewing the results of 72-hour fasting tests for five adult patients who developed neuroglycopenic symptoms with concurrent plasma glucose levels < 50 mg/dL. Match each patient's specific plasma laboratory profile, drawn at the precise time of symptomatic hypoglycemia, to the most likely underlying pathophysiologic etiology.

Click a left item, then click its matching right item

Show answer & explanation

Answer

The laboratory profiles uniquely differentiate the mechanisms of fasting hypoglycemia based on endogenous insulin secretion (C-peptide), beta-cell maturation (proinsulin), alternative insulin-receptor agonists (IGF-II), secretagogue presence, and the ketotic versus non-ketotic nature of the hypoglycemia.

Each laboratory profile distinctly aligns with a specific pathophysiologic mechanism of hypoglycemia. Factitious exogenous insulin provides the hormone without C-peptide. Insulinomas secrete mature insulin, C-peptide, and large amounts of proinsulin autonomously. Sulfonylureas drive normal endogenous secretion (increasing both insulin and C-peptide). NICTH relies on IGF-II activating insulin receptors systemically, which suppresses true insulin, C-peptide, and ketones. Finally, adrenal insufficiency causes hypoglycemia via impaired gluconeogenesis; the resulting appropriately suppressed insulin allows for unimpeded ketogenesis.

Step-by-Step Solution

1

Analyze insulin and C-peptide levels to differentiate exogenous from endogenous hyperinsulinism.

High insulin with suppressed C-peptide indicates an exogenous source, while high insulin with elevated C-peptide indicates an endogenous source.

C-peptide is co-secreted with endogenous insulin in equimolar amounts but is absent in pharmaceutical insulin preparations.

2

Differentiate endogenous hyperinsulinism etiologies using drug screens and proinsulin levels.

A positive screen confirms secretagogue use; a negative screen with disproportionately high proinsulin strongly points to an insulinoma.

Beta-cell neoplasms are less efficient at processing proinsulin to mature insulin compared to healthy beta cells stimulated by drugs.

3

Evaluate beta-hydroxybutyrate (ketone) levels to determine if the hypoglycemia is insulin-mediated.

Suppressed ketones indicate active suppression of lipolysis by an insulin-like effect (hyperinsulinism or IGF-II), whereas high ketones indicate appropriate insulin suppression (e.g., hypocortisolism).

Insulin strongly inhibits hormone-sensitive lipase, preventing ketone body formation.

Key Concept

Differential diagnosis of adult fasting hypoglycemia using the 72-hour fasting test.

Question 779Question →

Match each patient's clinical presentation with the most appropriate confirmatory diagnostic test.

Click a left item, then click its matching right item

Show answer & explanation

Answer

The presentations match as follows: SLE with spherocytes matches Direct antiglobulin test; Pancytopenia with portal vein thrombosis matches Flow cytometry for CD55 and CD59; Hemolysis post-nitrofurantoin matches G6PD enzyme assay; Pigment gallstones with high MCHC matches EMA binding test; Altered mental status with schistocytes matches ADAMTS13 activity assay.

Each clinical presentation contains classic pathognomonic findings that map to a highly specific diagnostic test for a particular hematologic disorder. The SLE patient with spherocytes has AIHA (Direct Coombs). The patient with pancytopenia and portal vein thrombosis has PNH (CD55/CD59). The patient with acute hemolysis after nitrofurantoin has G6PD deficiency (G6PD assay). The adolescent with pigment gallstones and high MCHC has hereditary spherocytosis (EMA binding). The patient with schistocytes, thrombocytopenia, and confusion has TTP (ADAMTS13).

Step-by-Step Solution

1

Analyze the first clinical presentation

SLE patient with hemolysis and spherocytes suggests warm autoimmune hemolytic anemia.

Systemic autoimmune diseases often produce IgG autoantibodies directed against red blood cell antigens.

2

Analyze the second clinical presentation

Pancytopenia, atypical venous thrombosis, and hemolysis point to paroxysmal nocturnal hemoglobinuria (PNH).

An acquired stem cell mutation leads to a lack of GPI anchors, making red blood cells highly susceptible to complement-mediated destruction.

3

Analyze the third clinical presentation

Hemolysis after a classic trigger (nitrofurantoin) with bite cells indicates Glucose-6-phosphate dehydrogenase deficiency.

Decreased NADPH production leads to oxidative damage of hemoglobin when exposed to specific medications or infections.

4

Analyze the fourth clinical presentation

A young patient with pigment gallstones, splenomegaly, and high MCHC suggests hereditary spherocytosis.

An inherited structural membrane defect leads to red blood cell dehydration, increasing the MCHC and causing splenic destruction.

5

Analyze the fifth clinical presentation

Thrombocytopenia, schistocytes, renal injury, and neurologic changes classically describe thrombotic thrombocytopenic purpura (TTP).

Microthrombi form systemically due to uncleaved, ultra-large von Willebrand factor multimers.

Key Concept

Clinical presentations and confirmatory diagnostics of hemolytic anemias and thrombotic microangiopathies

Question 780Question →

A 27-year-old woman presents to the gynecology clinic due to the absence of menses for nine months accompanied by spontaneous milky bilateral nipple discharge. She and her husband are hoping to have a child and have been having regular, unprotected intercourse for a year. A point-of-care urine pregnancy test is negative.

Arrange the following steps in the most appropriate chronological order for the evaluation and management of this patient to facilitate a safe pregnancy.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence is: biochemical evaluation (Prolactin/TSH), followed by anatomical evaluation (MRI), initiation of medical therapy (dopamine agonist), discontinuation of therapy upon conception, and finally clinical monitoring during pregnancy.

The correct sequence follows the standard guidelines for managing a prolactinoma in a patient seeking fertility: biochemical confirmation, anatomical diagnosis, medical management to restore ovulation, cessation of unnecessary medication upon conception, and clinical surveillance during gestation.

Step-by-Step Solution

1

Identify the primary presentation and rule out pregnancy

The patient has secondary amenorrhea and galactorrhea, with a negative beta-hCG test.

Pregnancy is the most common cause of secondary amenorrhea and must be excluded first.

2

Determine the initial diagnostic steps

Serum prolactin and TSH are measured to confirm hyperprolactinemia and exclude primary hypothyroidism.

Hypothyroidism can cause elevated TRH, which stimulates prolactin release.

3

Determine the next diagnostic step after biochemical confirmation

An MRI of the pituitary gland is performed.

Imaging is required to identify a pituitary adenoma and determine its size (microadenoma vs. macroadenoma).

4

Select the appropriate initial treatment

Therapy with a dopamine agonist (e.g., cabergoline) is initiated.

This medical therapy inhibits prolactin secretion, restores pulsatile GnRH release, and allows for ovulation.

5

Establish the management plan upon successful conception

The dopamine agonist is discontinued.

Stopping the medication prevents unnecessary fetal exposure, as microadenomas have a low risk of significant growth during pregnancy.

6

Establish the prenatal care plan regarding the adenoma

Clinical monitoring for headaches and visual field changes is instituted.

The pituitary naturally hypertrophies during pregnancy; if symptoms of tumor expansion occur, visual field testing and MRI may be indicated.

Key Concept

Evaluation and management sequence for hyperprolactinemia-induced infertility

Estimated Time:1m 15s

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