Examkin

All practice questions

1849 questions

All types8,270Multiple choice4,249Multiple select325Numeric160Matching1,849Ordering1,687
Question 1581Question →

Match each clinical presentation of an opportunistic infection in an immunocompromised patient with the most appropriate first-line targeted pharmacotherapy.

Click a left item, then click its matching right item

Items

Progressive exertional dyspnea, dry cough, and bilateral ground-glass opacities on chest CT. Sputum reveals cyst-like structures on silver stain.
Headache, confusion, and right-sided hemiparesis. Brain MRI demonstrates multiple ring-enhancing lesions in the basal ganglia.
Fever, profound weight loss, night sweats, and chronic diarrhea. Blood cultures grow a non-tuberculous mycobacterium.
Decreased visual acuity and floaters. Fundoscopic examination shows perivascular yellow-white retinal exudates with associated hemorrhage.

Matches

Show answer & explanation

Answer

Pneumocystis jirovecii matches with trimethoprim-sulfamethoxazole; Toxoplasma gondii matches with sulfadiazine, pyrimethamine, and leucovorin; Mycobacterium avium complex matches with azithromycin and ethambutol; Cytomegalovirus retinitis matches with valganciclovir.
The correct pairings accurately match each classic opportunistic clinical syndrome to its evidence-based, definitive antimicrobial therapy according to current infectious disease guidelines.

Step-by-Step Solution

1
Identify the fungal pathogen responsible for progressive dyspnea and silver stain-positive cysts.
Pneumocystis jirovecii.
Guides the selection of trimethoprim-sulfamethoxazole as the primary antimicrobial agent.
2
Identify the protozoan cause of multiple ring-enhancing basal ganglia lesions.
Toxoplasma gondii.
Directs selection of the targeted combination regimen of sulfadiazine, pyrimethamine, and leucovorin.
3
Identify the etiology of severe systemic symptoms, chronic diarrhea, and non-tuberculous mycobacteremia.
Disseminated Mycobacterium avium complex.
Directs selection of a multi-drug regimen including a macrolide (azithromycin) plus ethambutol to prevent resistance.
4
Identify the viral etiology of hemorrhagic retinal exudates.
Cytomegalovirus retinitis.
Requires specific anti-CMV therapy such as valganciclovir.

Key Concept

First-line pharmacotherapy for opportunistic infections in immunocompromised patients depends on accurately identifying the pathogen from classic clinical presentations and diagnostic findings.
Question 1582Question →

Match the following classic pediatric clinical presentations with their most likely causative viral pathogen.

Click a left item, then click its matching right item

Items

An infant presents with a generalized, rose-pink macular exanthem that appeared abruptly just after a continuous 72-hour period of elevated temperature normalized.
A school-aged child develops prominent bilateral cheek erythema, followed days later by a reticulated, erythematous eruption on the proximal extremities that worsens with warm baths.
An unvaccinated child exhibits a downward-spreading confluent exanthem accompanied by severe photophobia, coryza, and small white papules on the buccal mucosa.
An adolescent develops a faint pink, maculopapular eruption starting on the face and spreading downward, accompanied by prominent tender postauricular and suboccipital adenopathy.

Matches

Show answer & explanation

Answer

The presentations match chronologically and morphologically to their respective pathogens: abrupt rash after fever resolution matches Human herpesvirus 6; slapped cheeks and lacy rash match Parvovirus B19; severe prodrome with Koplik spots matches Measles virus; and mild cephalocaudal rash with postauricular adenopathy matches Rubella virus.
Each pediatric viral exanthem possesses distinct chronologic and morphologic features. Human herpesvirus 6 uniquely causes a rash that appears only after the fever breaks. Parvovirus B19 is identified by its lacy, reticular pattern following slapped-cheek erythema. Measles is diagnosed by severe prodromal toxicity, the 3 Cs, and Koplik spots prior to the coalescing rash. Rubella is identified by a milder presentation with characteristic tender occipital and postauricular adenopathy.

Step-by-Step Solution

1
Analyze the timeline of fever relative to the appearance of the rash.
Identify that the rash appearing strictly after defervescence is unique to Human herpesvirus 6 (Roseola).
Timeline is the primary diagnostic differentiator for Roseola infantum against other exanthems.
2
Evaluate associated prodromal symptoms and specific mucosal or physical exam findings.
Identify Koplik spots and severe coryza/photophobia as measles, and prominent suboccipital/postauricular adenopathy as rubella.
While both measles and rubella feature cephalocaudal spread, their associated prodromal toxicity and specific lymph node involvement definitively distinguish them.
3
Examine the specific morphology and triggers of the cutaneous eruption.
Identify the lacy, reticular pattern that flares with heat (like warm baths) as the hallmark of Parvovirus B19.
This distinct vascular reactivity is characteristic of Erythema infectiosum.

Key Concept

Differentiation of classic pediatric viral exanthems relies on the chronological relationship between fever and rash, distinct morphological patterns, and specific physical findings (e.g., Koplik spots, characteristic adenopathy).
Question 1583Question →

Match each patient's laboratory profile with the most likely underlying clinical etiology.

Click a left item, then click its matching right item

Items

ABG: pH 7.257.25, pCO 2_2 2424 mmHg, HCO 3−_3^- 1010 mEq/L. Serum: Na +^+ 140140 mEq/L, Cl −^- 105105 mEq/L
ABG: pH 7.527.52, pCO 2_2 4848 mmHg, HCO 3−_3^- 3838 mEq/L. Urine Cl −^- 88 mEq/L
ABG: pH 7.287.28, pCO 2_2 6060 mmHg, HCO 3−_3^- 2626 mEq/L
ABG: pH 7.317.31, pCO 2_2 3030 mmHg, HCO 3−_3^- 1515 mEq/L. Serum: Na +^+ 135135 mEq/L, Cl −^- 112112 mEq/L
ABG: pH 7.447.44, pCO 2_2 2828 mmHg, HCO 3−_3^- 1919 mEq/L

Matches

Show answer & explanation

Answer

The correct matches require calculating the anion gap and assessing respiratory compensation chronicity to identify the primary acid-base disorder and its etiology.
Each laboratory profile represents a classic presentation of a primary acid-base disorder with appropriate physiologic compensation. Matching them accurately requires systematic calculation of the anion gap, expected compensation formulas, and an understanding of volume status via urine electrolytes.

Step-by-Step Solution

1
Calculate the anion gap (Na+−(Cl−+HCO3−)\text{Na}^+ - (\text{Cl}^- + \text{HCO}_3^-)) for the metabolic acidosis profiles (Profiles 1 and 4).
Profile 1 has an AG of 2525 mEq/L (HAGMA), while Profile 4 has an AG of 88 mEq/L (NAGMA).
Differentiating HAGMA from NAGMA isolates uncontrolled diabetes (HAGMA) from severe diarrhea (NAGMA).
2
Evaluate the metabolic alkalosis profile (Profile 2) using urine chloride.
Profile 2 shows a low urine chloride (88 mEq/L).
Low urine chloride (<20< 20 mEq/L) indicates a saline-responsive alkalosis, typically caused by upper gastrointestinal fluid loss such as hyperemesis gravidarum.
3
Analyze the ratio of change in pCO 2_2 to HCO 3−_3^- for the respiratory disorders (Profiles 3 and 5) to determine acuity.
Profile 3 shows an acute 11:1010 ratio of HCO 3−_3^- increase to pCO 2_2 increase. Profile 5 shows a chronic 44:1010 to 55:1010 ratio of HCO 3−_3^- decrease to pCO 2_2 decrease.
This distinguishes the acute hypoventilation of a heroin overdose from the chronic, progesterone-driven hyperventilation of a normal third-trimester pregnancy.

Key Concept

Interpretation of arterial blood gases and electrolyte panels to diagnose specific acid-base disorders
Question 1584Question →

Match each classic clinical presentation with its most likely esophageal diagnosis.

Click a left item, then click its matching right item

Items

A 45-year-old patient with dysphagia to both solids and liquids, regurgitation of undigested food, and a 'bird's beak' appearance on a barium swallow study.
A 60-year-old patient with a long history of untreated gastroesophageal reflux disease who now reports progressive dysphagia initially to solid foods, accompanied by unintentional weight loss.
A 35-year-old patient presenting with severe, retrosternal chest pain and subcutaneous emphysema in the neck following multiple episodes of forceful retching.
A 40-year-old patient presenting with episodic, severe, non-cardiac chest pain and a 'corkscrew' appearance on a barium swallow study.

Matches

Show answer & explanation

Answer

The patient with a 'bird's beak' appearance matches Achalasia. The patient with chronic GERD and progressive dysphagia matches Esophageal adenocarcinoma. The patient with transmural rupture following forceful vomiting matches Boerhaave syndrome. The patient with a 'corkscrew' esophagus matches Diffuse esophageal spasm.
Each clinical vignette provides pathognomonic features for a specific esophageal pathology, allowing direct diagnosis based on classic illness scripts expected for the exam.

Step-by-Step Solution

1
Analyze the first clinical vignette describing dysphagia to solids and liquids with a 'bird's beak' appearance.
Identified as Achalasia.
Achalasia is characterized by loss of primary peristalsis and failure of lower esophageal sphincter relaxation, leading to this classic radiologic finding.
2
Analyze the second vignette describing progressive dysphagia to solids and weight loss in a patient with chronic GERD.
Identified as Esophageal adenocarcinoma.
Chronic GERD is a major risk factor for Barrett's esophagus, which can transform into adenocarcinoma, typically presenting with mechanical obstruction.
3
Analyze the third vignette describing severe chest pain and subcutaneous emphysema after forceful retching.
Identified as Boerhaave syndrome.
Transmural esophageal rupture allows air to escape into the mediastinum and subcutaneous tissues, causing pneumomediastinum and crepitus.
4
Analyze the fourth vignette describing episodic chest pain and a 'corkscrew' esophagus.
Identified as Diffuse esophageal spasm.
Simultaneous, uncoordinated esophageal contractions create the classic 'corkscrew' appearance on a contrast swallow study.

Key Concept

Classic clinical presentations and radiologic findings of major esophageal disorders.
Question 1585Question →

Connect the following antineoplastic agents with their most characteristic adverse effect that dictates specific clinical monitoring or preventive management.

Click a left item, then click its matching right item

Items

Trastuzumab
Bleomycin
Cyclophosphamide
Doxorubicin

Matches

Show answer & explanation

Answer

Trastuzumab pairs with non-dose-dependent reversible cardiomyopathy; Bleomycin pairs with pulmonary fibrosis; Cyclophosphamide pairs with acrolein-mediated hemorrhagic cystitis; Doxorubicin pairs with cumulative irreversible dilated cardiomyopathy.
Each antineoplastic agent has a well-defined toxicity profile that necessitates specific screening and prevention. Trastuzumab requires periodic echocardiograms to monitor for a reversible drop in left ventricular ejection fraction. Bleomycin requires baseline and follow-up pulmonary function testing due to the risk of interstitial lung disease. Cyclophosphamide requires aggressive intravenous hydration and co-administration of mesna to prevent acrolein-induced hemorrhagic cystitis. Doxorubicin requires strict tracking of the patient's lifetime cumulative dose to prevent irreversible, free radical-mediated dilated cardiomyopathy.

Step-by-Step Solution

1
Differentiate between the distinct cardiotoxic profiles of Trastuzumab and Doxorubicin.
Trastuzumab causes Type II cardiotoxicity (reversible, non-dose-dependent), while Doxorubicin causes Type I cardiotoxicity (irreversible, dose-dependent).
Both cause heart failure, but understanding the reversibility determines long-term monitoring and treatment cessation strategies.
2
Identify the classic pulmonary toxicity.
Bleomycin is matched with interstitial pneumonitis and pulmonary fibrosis.
Bleomycin clearance is reduced in the lungs, predisposing lung tissue to severe free radical damage and eventual fibrosis.
3
Identify the mechanism of urothelial toxicity.
Cyclophosphamide is matched with hemorrhagic cystitis.
Acrolein, a toxic metabolite of cyclophosphamide, accumulates in the bladder and must be actively neutralized with aggressive hydration and mesna.

Key Concept

Adverse effects of antineoplastic agents
Question 1586Question →

Hepatitis B virus (HBV) infection can present in various clinical phases, each characterized by a distinct serologic profile. Match each clinical status with its most representative hepatitis B serologic panel.

Click a left item, then click its matching right item

Items

Acute hepatitis B infection (window period)
Chronic inactive hepatitis B carrier
Resolved natural hepatitis B infection
Immunity due to hepatitis B vaccination
Chronic hepatitis B infection (high infectivity)

Matches

Show answer & explanation

Answer

The correct matches map the window period to isolated Anti-HBc IgM, the inactive carrier to HBsAg (+)/normal ALT, resolved infection to Anti-HBs/Anti-HBc IgG, vaccination to isolated Anti-HBs, and high infectivity chronic infection to HBsAg (+)/HBeAg (+).
Each specific clinical phase of Hepatitis B corresponds directly to its unique pattern of surface, core, and envelope antigens and their respective antibodies, as well as the presence of active liver inflammation.

Step-by-Step Solution

1
Analyze the HBsAg status for each clinical scenario.
Active/chronic infections have HBsAg (+). Resolved infections, vaccinated patients, and window period patients have HBsAg (-).
HBsAg is the hallmark of active viral presence.
2
Differentiate the HBsAg (-) states.
Vaccination has isolated Anti-HBs (+). Resolved natural infection has Anti-HBs (+) AND Anti-HBc IgG (+). The window period has isolated Anti-HBc IgM (+).
Vaccines only contain surface antigen. Natural infection exposes the patient to core antigen. The window period occurs before surface antibodies rise.
3
Differentiate the HBsAg (+) states.
High infectivity is marked by HBeAg (+) and elevated ALT. The inactive carrier state has HBeAg (-) and normal ALT.
HBeAg correlates with viral replication and infectivity, which drives active liver inflammation (elevated ALT).

Key Concept

Interpretation of Hepatitis B serological markers to determine disease phase.
Question 1587Question →

Match each distinct clinical presentation of acute third-trimester or intrapartum bleeding with its most likely underlying obstetric complication.

Click a left item, then click its matching right item

Items

Painless, bright red vaginal bleeding with a soft, non-tender uterus
Sudden-onset severe abdominal pain, a rigid uterus, and dark vaginal bleeding
Painless vaginal bleeding immediately following artificial rupture of membranes, accompanied by a sinusoidal fetal heart rate
Sudden tearing lower abdominal pain, rapid cessation of uterine contractions, and loss of fetal station during a trial of labor

Matches

Show answer & explanation

Answer

Painless bleeding with a soft uterus matches Placenta previa. Painful rigid uterus matches Abruptio placentae. Post-amniotomy bleeding with a sinusoidal fetal tracing matches Vasa previa. Loss of station with pain matches Uterine rupture.
Each etiology of obstetric hemorrhage has hallmark clinical signs: placenta previa is painless with normal uterine tone, abruptio placentae features a tender and hypertonic uterus, vasa previa is directly linked to membrane rupture and triggers rapid fetal exsanguination, and uterine rupture uniquely presents with loss of fetal station and sudden cessation of contractions.

Step-by-Step Solution

1
Evaluate the presence or absence of abdominal pain and uterine tone.
Pain and a rigid uterus point to abruptio placentae or uterine rupture, whereas painless bleeding suggests placenta previa or vasa previa.
Myometrial irritation differentiates structural tears or concealed bleeding from superficial implantation bleeding.
2
Analyze the timing of bleeding relative to amniotic membrane rupture.
Bleeding precisely coinciding with artificial rupture of membranes strongly indicates torn fetal vessels.
In vasa previa, the aberrant fetal vessels cross the internal os and are physically sheared when the amniotic sac ruptures.
3
Assess labor progression anomalies and fetal station changes.
A sudden loss of fetal station combined with cessation of contractions confirms uterine rupture.
When the uterus completely tears, it loses the ability to contract, and the fetus recedes out of the birth canal into the peritoneal cavity.

Key Concept

Clinical differentiation of late-pregnancy hemorrhage
Estimated Time:1m 30s
Question 1588Question →

Match each of the following clinical presentations with the most likely diagnosis.

Click a left item, then click its matching right item

Items

A 45-year-old man presents with chronic diarrhea, profound weight loss, migratory polyarthralgia, and subtle cognitive decline. Small bowel biopsy reveals periodic acid-Schiff (PAS)-positive, diastase-resistant inclusions in lamina propria macrophages.
A 32-year-old woman presents with chronic diarrhea, weight loss, severe iron deficiency anemia, and an intensely pruritic, papulovesicular rash on her elbows and knees.
A 58-year-old man presents with episodic, intense facial flushing, chronic watery diarrhea, and a newly auscultated holosystolic murmur at the left lower sternal border that increases with inspiration.
A 40-year-old woman presents with massive volumes of tea-colored watery diarrhea (up to 5 liters daily), severe muscle cramps, and profound muscle weakness. Laboratory testing reveals severe hypokalemia and achlorhydria.

Matches

Show answer & explanation

Answer

1 matches with Whipple disease; 2 matches with Celiac disease; 3 matches with Carcinoid syndrome; 4 matches with VIPoma.
Each clinical presentation aligns precisely with a distinct gastroenterologic syndrome characterized by its pathognomonic features: PAS-positive macrophages for Whipple disease, dermatitis herpetiformis for celiac disease, right-sided heart disease with flushing for carcinoid syndrome, and the WDHA triad for VIPoma.

Step-by-Step Solution

1
Analyze the first vignette focusing on the PAS-positive macrophages and systemic manifestations.
Identified as Whipple disease due to the classic combination of malabsorption, arthralgias, neurologic symptoms, and histologic findings.
PAS-positive macrophages are pathognomonic for Tropheryma whipplei infection in the context of these clinical symptoms.
2
Evaluate the second vignette highlighting the dermatologic and hematologic findings.
Identified as Celiac disease.
The combination of malabsorption, iron deficiency anemia, and dermatitis herpetiformis is classically seen in celiac disease due to gluten sensitivity.
3
Examine the third vignette focusing on episodic flushing and cardiac involvement.
Identified as Carcinoid syndrome.
Serotonin secretion from a carcinoid tumor leads to flushing, diarrhea, and right-sided valvular heart lesions (tricuspid regurgitation).
4
Assess the fourth vignette noting the biochemical triad.
Identified as VIPoma.
The presentation of watery diarrhea, severe hypokalemia, and achlorhydria constitutes the WDHA syndrome caused by a VIP-secreting tumor.

Key Concept

Differential diagnosis of chronic diarrhea syndromes based on characteristic systemic, dermatologic, and biochemical manifestations.
Question 1589Question →

Match each clinical presentation with its underlying pathophysiologic mechanism or characteristic pathologic finding.

Click a left item, then click its matching right item

Items

A 32-year-old man reports chronic, insidious-onset low back pain and stiffness that is worst in the morning, improves significantly with physical activity, and occasionally awakens him in the second half of the night.
A 26-year-old woman of Mediterranean descent presents with painful, recurrent aphthous ulcers in her mouth and on her labia, accompanied by recent visual disturbances and anterior uveitis.
A 48-year-old woman develops symmetric, proximal muscle weakness making it difficult to comb her hair, accompanied by a violaceous periorbital eruption and scaly plaques on the extensor surfaces of her metacarpophalangeal joints.
A 42-year-old woman describes months of widespread, achy musculoskeletal pain, profound fatigue, unrefreshing sleep, and tenderness at multiple points, with entirely normal laboratory inflammatory markers.

Matches

Show answer & explanation

Answer

The correct pairings match each patient's clinical presentation to the underlying disease pathophysiology: the man with inflammatory back pain has Ankylosing Spondylitis (driven by enthesitis), the woman with recurrent ulcers has Behçet syndrome (a systemic vasculitis with pathergy), the woman with muscle weakness and rash has Dermatomyositis (complement-mediated microangiopathy), and the woman with widespread pain without inflammation has Fibromyalgia (central sensitization).
Each vignette represents a classic presentation of a distinct rheumatologic disorder, perfectly aligning with one distinct pathophysiologic mechanism provided in the options. Diagnosing the condition based on the constellation of symptoms allows for direct correlation to its pathologic basis.

Step-by-Step Solution

1
Analyze each clinical vignette to establish the most likely diagnosis.
Patient 1 has ankylosing spondylitis; Patient 2 has Behçet syndrome; Patient 3 has dermatomyositis; Patient 4 has fibromyalgia.
Identifying the specific rheumatologic condition is the necessary first step before determining its underlying mechanism.
2
Evaluate the pathophysiologic descriptions and link them to the identified diagnoses.
Ankylosing spondylitis pairs with enthesitis; Behçet syndrome pairs with vasculitis/pathergy; dermatomyositis pairs with complement-mediated microangiopathy; fibromyalgia pairs with central pain sensitization.
Matching the disease to its core pathologic mechanism confirms understanding of disease etiology as tested on the exam.

Key Concept

Pathophysiologic mechanisms of common rheumatologic and autoimmune conditions.
Question 1590Question →

Match the following clinical presentations of acute trauma to the most appropriate initial diagnostic or therapeutic intervention according to standard trauma protocols.

Click a left item, then click its matching right item

Items

Stab wound to the left parasternal space with hypotension, distended neck veins, and clear lung fields bilaterally.
High-speed collision victim with a widened mediastinum on chest radiograph and unequal blood pressures in the upper extremities.
Blunt chest trauma with severe respiratory distress, hypotension, tracheal deviation to the left, and absent right-sided breath sounds.
Stab wound to the anterior neck with an expanding hematoma, stridor, and subcutaneous emphysema.

Matches

Show answer & explanation

Answer

Tamponade presentation matches echocardiography; blunt aortic injury presentation matches CT angiography; tension pneumothorax presentation matches immediate decompression; penetrating neck trauma with hard signs matches immediate operative exploration.
Each clinical scenario corresponds to a distinct, life-threatening trauma pathway. Tension pneumothorax requires immediate clinical decompression. Cardiac tamponade requires sonographic confirmation and drainage. Blunt aortic injury in a hemodynamically stable patient requires CT angiography. Penetrating neck trauma presenting with hard signs requires immediate operative control and airway securement.

Step-by-Step Solution

1
Analyze the first presentation (left parasternal stab wound, hypotension, distended neck veins, clear lungs).
Identify Beck's triad, indicating cardiac tamponade.
Clear lung fields rule out tension pneumothorax in this context, isolating the heart as the source of obstructive shock.
2
Analyze the second presentation (deceleration injury, widened mediastinum, pulse discrepancy).
Identify the high risk for blunt thoracic aortic injury.
The mechanism and radiographic findings dictate the need for definitive vascular imaging.
3
Analyze the third presentation (respiratory distress, hypotension, tracheal deviation, absent breath sounds).
Identify tension pneumothorax.
This is a purely clinical diagnosis requiring immediate intervention, not imaging.
4
Analyze the fourth presentation (anterior neck stab wound, expanding hematoma, stridor).
Identify hard signs of penetrating neck trauma.
Hard signs indicate imminent airway loss or exsanguination, requiring immediate surgical management.

Key Concept

Advanced Trauma Life Support (ATLS) specific interventions based on primary survey findings
Question 1591Question →

Evaluate the following four clinical scenarios describing patients with symptomatic thyrotoxicosis. Match each clinical vignette to the specific histopathologic or molecular etiology driving the patient's condition.

Click a left item, then click its matching right item

Items

A 26-year-old woman presents with unintentional weight loss, prominent exophthalmos, and pretibial skin thickening. Laboratory tests reveal a suppressed TSH and elevated free T4. A radioactive iodine uptake (RAIU) scan demonstrates a diffuse, homogeneous pattern of increased uptake throughout the gland.
A 39-year-old woman presents with severe anterior neck pain, low-grade fever, and tremors 3 weeks after a respiratory viral infection. Labs show suppressed TSH, elevated free T4, and an erythrocyte sedimentation rate (ESR) of 85 mm/hr. RAIU is less than 1%.
A 71-year-old woman with new-onset atrial fibrillation presents with palpitations. Physical exam reveals a palpable, lumpy, and asymmetrical thyroid gland. Labs show suppressed TSH and elevated free T4. RAIU scan shows multiple patchy areas of intensely increased uptake interspersed with areas of absent uptake.
A 32-year-old woman presents with anxiety and palpitations 4 months after delivering a healthy infant. The thyroid is entirely painless and normal in size on palpation. Labs show suppressed TSH, elevated free T4, and a normal ESR. RAIU is less than 1%.

Matches

Show answer & explanation

Answer

The correct pairings identify Graves disease (autoantibodies activating receptors), subacute thyroiditis (granulomatous destruction), toxic multinodular goiter (autonomous focal production), and postpartum thyroiditis (lymphocytic infiltration).
Graves disease is driven by TSH receptor-stimulating autoantibodies, leading to diffuse iodine uptake. Subacute thyroiditis involves viral-induced granulomatous destruction, causing a painful goiter and low uptake due to follicular rupture. Toxic multinodular goiter involves autonomous nodules, showing patchy uptake on imaging. Postpartum thyroiditis is a painless lymphocytic inflammation occurring within a year of delivery, also causing low uptake due to the release of preformed hormone.

Step-by-Step Solution

1
Analyze the radioactive iodine uptake (RAIU) and physical exam findings for each clinical scenario.
Scenarios 1 and 3 demonstrate increased uptake, indicating true hyperthyroidism (increased de novo hormone synthesis). Scenarios 2 and 4 demonstrate decreased uptake, indicating a destructive thyroiditis (release of preformed hormone).
RAIU separates thyrotoxicosis into states of overproduction versus states of glandular destruction or exogenous intake.
2
Differentiate the hyperthyroid states (Scenarios 1 and 3).
Scenario 1 describes diffuse uptake with unique extrathyroidal manifestations (exophthalmos), pointing to Graves disease (autoantibody-mediated). Scenario 3 describes patchy uptake with a lumpy gland in an older adult, pointing to toxic multinodular goiter (autonomous focal nodules).
The pattern of uptake (diffuse vs. patchy) correlates directly with the underlying diffuse molecular trigger versus focal somatic mutations.
3
Differentiate the destructive thyroiditis states (Scenarios 2 and 4).
Scenario 2 features a painful neck, high ESR, and viral prodrome, indicating subacute granulomatous thyroiditis. Scenario 4 features a painless neck in a postpartum patient, indicating postpartum lymphocytic thyroiditis.
Pain and systemic inflammation distinguish granulomatous destruction from painless autoimmune lymphocytic destruction.

Key Concept

Differential diagnosis of thyrotoxicosis utilizing clinical presentation, physical examination, and radioactive iodine uptake patterns to identify underlying pathophysiologic mechanisms.
Question 1592Question →

Review the following clinical scenarios involving patients with diverticular disease. Correlate each specific presentation with its most appropriate next step in management based on current clinical guidelines.

Click a left item, then click its matching right item

Items

A 50-year-old healthy man with mild left lower quadrant pain and CT-confirmed acute uncomplicated diverticulitis without systemic toxicity.
A 62-year-old woman with acute diverticulitis who is found on CT scan to have a well-defined 5-cm pericolic fluid collection.
A 70-year-old man with acute diverticulitis presenting with diffuse abdominal rigidity, hypotension, and large volume free intraperitoneal air.
A 55-year-old woman with a history of five episodes of uncomplicated diverticulitis in the past two years requesting definitive management.

Matches

Show answer & explanation

Answer

Match mild uncomplicated diverticulitis to conservative management without antibiotics; abscess >4cm to percutaneous drainage; purulent/feculent peritonitis to emergent laparotomy; and frequent recurrent episodes to elective resection.
The correct pairings align with current clinical guidelines for diverticular disease, which stratify treatment by disease severity (uncomplicated vs. complicated) and the presence of hemodynamic instability or peritonitis.

Step-by-Step Solution

1
Analyze the first scenario (mild uncomplicated diverticulitis).
Identify a lack of systemic toxicity or surgical complications.
Determines that conservative therapy without antibiotics is the standard of care to prevent antimicrobial resistance.
2
Analyze the second scenario (5-cm pericolic fluid collection).
Identify complicated diverticulitis with a large abscess.
Abscesses >3-4 cm generally require percutaneous drainage in addition to therapeutic antibiotics.
3
Analyze the third scenario (diffuse rigidity, hypotension, free air).
Identify generalized peritonitis (Hinchey III/IV).
Life-threatening peritonitis requires immediate surgical exploration, typically with a Hartmann procedure, as medical management will fail.
4
Analyze the fourth scenario (recurrent uncomplicated episodes).
Identify a severe quality-of-life impact from chronic recurrences.
Patients with multiple symptomatic recurrences are ideal candidates for elective sigmoid resection to prevent future episodes.

Key Concept

Management of Diverticular Disease
Question 1593Question →

Match each clinical presentation of glomerular disease with its most characteristic renal biopsy or immunofluorescence finding.

Click a left item, then click its matching right item

Items

A 24-year-old man with episodic gross hematuria occurring concurrently with viral upper respiratory tract infections.
A 9-year-old boy with hypertension, periorbital edema, and dark urine two weeks after resolving impetigo.
A 30-year-old man presenting with acute kidney injury, hemoptysis, and bilateral alveolar infiltrates.
A 65-year-old man with a history of colon adenocarcinoma presenting with severe peripheral edema, proteinuria of 4.5 g/day, and hypoalbuminemia.

Matches

Show answer & explanation

Answer

IgA nephropathy matches with mesangial IgA deposition; PSGN matches with subepithelial humps; Goodpasture syndrome matches with linear IgG deposition; Membranous nephropathy matches with subepithelial 'spike and dome' deposits.
Each clinical scenario distinctly describes a specific glomerular disease that corresponds precisely to a unique pathological finding: IgA nephropathy correlates with mesangial deposits, PSGN with subepithelial humps, Goodpasture syndrome with linear IgG deposition, and membranous nephropathy with a spike and dome pattern.

Step-by-Step Solution

1
Analyze the first clinical vignette regarding the timing of hematuria relative to the upper respiratory infection.
The concurrent nature of the hematuria and infection identifies IgA nephropathy.
Synpharyngitic hematuria differentiates IgA nephropathy from post-infectious etiologies, and is confirmed by mesangial IgA deposition on biopsy.
2
Evaluate the second presentation involving a pediatric patient with delayed-onset hematuria and edema following a skin infection.
The distinct latency period of two weeks points to poststreptococcal glomerulonephritis (PSGN).
PSGN requires time for immune complex formation and deposition, classically forming subepithelial humps visible on electron microscopy.
3
Assess the third patient presenting with rapidly progressive pulmonary-renal syndrome.
Hemoptysis combined with acute kidney injury strongly suggests Goodpasture syndrome.
Anti-glomerular basement membrane (anti-GBM) antibodies attack both alveolar and glomerular basement membranes, yielding a linear IgG immunofluorescence pattern.
4
Examine the adult patient with nephrotic range proteinuria and an underlying malignancy.
The clinical picture correlates with membranous nephropathy.
Solid organ tumors are classic secondary causes of membranous nephropathy, which reveals subepithelial deposits generating a 'spike and dome' appearance on silver staining.

Key Concept

Identifying primary and secondary glomerular diseases based on their classic clinical presentations and pathognomonic histopathological findings.
Estimated Time:1m 30s
Question 1594Question →

Match each clinical presentation and coagulation laboratory profile to the most likely underlying hematologic diagnosis.

Click a left item, then click its matching right item

Items

A 42-year-old hospitalized man with gram-negative bacteremia develops spontaneous oozing from his intravenous catheter sites. Laboratory studies reveal prolonged prothrombin time (PT), prolonged activated partial thromboplastin time (aPTT), significantly decreased fibrinogen, and thrombocytopenia.
A 16-year-old girl is evaluated for heavy menstrual bleeding since menarche and recurrent epistaxis. Laboratory studies reveal a normal PT, mildly prolonged aPTT, normal platelet count, and prolonged bleeding time.
A 9-year-old boy presents with severe right knee pain, warmth, and swelling following a minor trip and fall. Laboratory studies reveal a normal PT, markedly prolonged aPTT, normal platelet count, and normal bleeding time.
A 28-year-old woman presents with newly developed scattered petechiae over her lower extremities following a recent upper respiratory tract infection. Laboratory studies reveal a normal PT, normal aPTT, normal fibrinogen, and a platelet count of 12,000/mm³.

Matches

Show answer & explanation

Answer

The presentations match with DIC, von Willebrand disease, Hemophilia A, and ITP respectively, based on whether the defect involves primary hemostasis, secondary hemostasis, or broad factor consumption.
Correct matching requires distinguishing between primary hemostasis disorders (involving platelets and von Willebrand factor, presenting with mucocutaneous bleeding and prolonged bleeding time) and secondary hemostasis disorders (involving coagulation factors, presenting with deep tissue bleeding and prolonged PT/aPTT).

Step-by-Step Solution

1
Analyze the PT and aPTT results.
Determines if the defect is in the extrinsic, intrinsic, or common coagulation pathway (secondary hemostasis).
Isolated aPTT prolongation points to the intrinsic pathway (e.g., Hemophilia), while prolongation of both suggests a consumptive process like DIC.
2
Evaluate the platelet count and bleeding time.
Differentiates primary hemostasis disorders from secondary hemostasis disorders.
Abnormalities here suggest platelet destruction (e.g., ITP) or dysfunction (e.g., von Willebrand disease, which affects platelet adhesion).
3
Integrate laboratory findings with the clinical vignette.
Confirms the specific etiology.
Clinical context like sepsis (DIC), joint bleeding (Hemophilia), mucosal bleeding (vWD), or post-viral petechiae (ITP) secures the diagnosis.

Key Concept

Diagnosis of bleeding disorders using clinical presentation and coagulation profiles
Question 1595Question →

Match each clinical presentation of infective endocarditis with the most likely causative microorganism.

Click a left item, then click its matching right item

Items

An individual with active injection drug use presenting with high fever, tricuspid valve vegetations, and scattered cavitary pulmonary infiltrates.
An older adult who develops subacute infective endocarditis shortly after undergoing cystoscopy and transurethral prostatectomy.
A patient diagnosed with native valve endocarditis who is concurrently found to have an asymptomatic ascending colon adenocarcinoma.
A patient hospitalized for high-grade bacteremia and paravalvular regurgitation noted four weeks following mechanical prosthetic valve implantation.
A previously healthy individual with a known structural heart defect who develops slowly progressive fatigue and splinter hemorrhages following extensive dental work.

Matches

Show answer & explanation

Answer

The presentations map to established clinical risk factors: injection drug use links to Staphylococcus aureus, genitourinary procedures to Enterococcus faecalis, colon cancer to Streptococcus gallolyticus, early prosthetic valves to Staphylococcus epidermidis, and dental procedures to Viridans group streptococci.
Each matching pair relies on classic pathophysiologic associations. Staphylococcus aureus dominates in intravenous drug users due to skin flora introduction into venous circulation. Enterococcus faecalis is linked to genitourinary tract instrumentation. Streptococcus gallolyticus has a strong association with colorectal malignancy. Staphylococcus epidermidis relies on its biofilm-producing capabilities to infect foreign hardware like recently placed mechanical valves. Finally, Viridans group streptococci reside in the oral cavity and enter the bloodstream during dental procedures to infect structurally abnormal native valves.

Step-by-Step Solution

1
Identify the unique precipitating clinical risk factor in each patient vignette.
The identified risk factors are: intravenous drug use, recent genitourinary manipulation, undiagnosed colon cancer, recent cardiac valve replacement, and significant dental work.
Pathogens responsible for infective endocarditis are highly predictable based on the mechanism of bacteremia and patient history.
2
Correlate each identified risk factor with its classic microbiological flora.
Drug use matches S. aureus; GU tract matches Enterococcus; colon cancer matches S. gallolyticus; prosthetic materials match S. epidermidis; and the oral cavity matches Viridans streptococci.
Definitive empiric treatment and appropriate diagnostic follow-up require anticipation of the correct organism based on patient characteristics.

Key Concept

Risk-factor associations for causative organisms in infective endocarditis.
Question 1596Question →

Match each of the following clinical vignettes and laboratory profiles to the most accurate underlying pathophysiologic mechanism.

Click a left item, then click its matching right item

Items

A 2828-year-old with bipolar disorder presenting with polyuria. Laboratory evaluation shows serum Na+Na^+ 148148 mEq/L and urine osmolality 120120 mOsm/kg. Exogenous desmopressin administration produces no significant change in urine osmolality.
A 4545-year-old recovering from transsphenoidal adenomectomy develops excessive thirst. Laboratory evaluation shows serum Na+Na^+ 149149 mEq/L and urine osmolality 140140 mOsm/kg. Desmopressin administration increases urine osmolality to 580580 mOsm/kg.
A 6565-year-old with a chronic cough and weight loss presents with confusion. Laboratory evaluation shows serum Na+Na^+ 122122 mEq/L, urine osmolality 550550 mOsm/kg, and urine Na+Na^+ 4545 mEq/L.
A 3434-year-old with schizophrenia reports drinking 88 liters of water daily. Laboratory evaluation shows serum Na+Na^+ 131131 mEq/L and urine osmolality 8585 mOsm/kg. A supervised water deprivation test gradually increases urine osmolality to 600600 mOsm/kg.

Matches

Show answer & explanation

Answer

The correct matches pair the lithium patient with renal resistance (nephrogenic DI), the post-surgical patient with deficient pituitary release (central DI), the patient with suspected lung malignancy with unregulated excess ADH (SIADH), and the compulsive water drinker with physiologic ADH suppression (primary polydipsia).
Matching these conditions requires synthesizing baseline sodium, baseline urine concentration, and dynamic testing results. Hypernatremic patients with dilute urine have diabetes insipidus (DI); a history of lithium therapy combined with a failure to respond to desmopressin confirms nephrogenic DI (renal resistance), whereas a history of pituitary surgery and a robust response to desmopressin confirms central DI (deficient release). Hyponatremic patients with inappropriately concentrated urine have SIADH (unregulated excess ADH), frequently driven by ectopic production from a malignancy. Hyponatremic patients with appropriately dilute urine who subsequently concentrate their urine during water deprivation have primary polydipsia (appropriate physiologic suppression of ADH).

Step-by-Step Solution

1
Analyze baseline serum sodium to determine overall body water status.
Hypernatremia (>145>145 mEq/L) indicates a primary loss of free water (diabetes insipidus), whereas hyponatremia (<135<135 mEq/L) indicates primary water retention (SIADH or primary polydipsia).
This fundamental step categorizes the patient into a water-losing versus water-retaining state.
2
Evaluate baseline urine osmolality in the context of the serum sodium.
Low urine osmolality (<300<300 mOsm/kg) despite hypernatremia confirms a severe concentrating defect. High urine osmolality (>100>100 mOsm/kg) despite hyponatremia confirms an inability to dilute the urine.
Urine osmolality demonstrates whether the kidneys are responding appropriately to the abnormal serum tonicity.
3
Interpret the response to dynamic testing (desmopressin administration or water deprivation).
A response to desmopressin differentiates central DI (responds) from nephrogenic DI (does not respond). A normal response to water deprivation differentiates primary polydipsia (concentrates normally once water is withheld) from DI.
Dynamic testing isolates the specific anatomical failure point (brain versus kidney) or behavioral cause in the antidiuretic hormone axis.

Key Concept

Diagnosis of Polyuria and Sodium Derangements via the ADH Axis
Question 1597Question →

Following the primary survey and initial resuscitation in the trauma bay, the next steps in management diverge significantly based on the patient's hemodynamic status, mechanism of injury, and bedside diagnostic findings. Match each clinical presentation below with the most appropriate immediate diagnostic or therapeutic next step.

Click a left item, then click its matching right item

Items

40-year-old man post-collision; BP 75/40 mm Hg; bedside trauma ultrasound is negative for intraperitoneal fluid; pelvic radiograph shows symphyseal diastasis despite binder application.
22-year-old woman with a periumbilical stab wound; BP 80/50 mm Hg; physical exam reveals a rigid, board-like abdomen.
30-year-old man struck by car; BP 125/80 mm Hg; bedside trauma ultrasound demonstrates free fluid in the hepatorenal recess.
55-year-old woman after a 15-foot fall; BP 115/75 mm Hg; portable chest radiograph demonstrates a widened mediastinum.
28-year-old man with a stab wound to the left fifth intercostal space; BP 60/palpable; distended neck veins and distant heart sounds.

Matches

Show answer & explanation

Answer

The presentations match as follows: Unstable pelvic fracture with negative ultrasound goes to pelvic angiography. Unstable penetrating abdominal trauma goes to emergent surgical abdominal exploration. Stable blunt trauma with positive ultrasound goes to cross-sectional imaging of the abdomen/pelvis. Stable blunt trauma with widened mediastinum goes to CT vascular imaging of the thorax. Unstable penetrating chest trauma with tamponade signs goes to emergent pericardial window or thoracotomy.
The correct matches strictly align with standard trauma protocols, which dictate that hemodynamic stability is the primary decision point for determining whether a patient can undergo cross-sectional imaging or requires immediate hemorrhage control via surgical exploration or angiography.

Step-by-Step Solution

1
Assess the hemodynamic status of each patient.
The patients in scenarios 1, 2, and 5 are hemodynamically unstable (hypotensive). The patients in scenarios 3 and 4 are hemodynamically stable.
Hemodynamic stability is the primary branch point in trauma algorithms, dictating whether a patient can safely leave the resuscitation bay for diagnostic imaging.
2
Evaluate the mechanism and bedside findings for the unstable patients.
The first patient has a pelvic source of bleeding (requires angiography). The second patient has a penetrating abdominal source with peritonitis (requires surgical exploration). The fifth patient has penetrating chest trauma with tamponade (requires surgical decompression).
Unstable patients require immediate, definitive hemorrhage control based on the most likely anatomical source of bleeding identified at the bedside.
3
Determine the appropriate advanced diagnostic imaging for the stable patients.
The third patient undergoes cross-sectional imaging of the abdomen to evaluate the fluid seen on ultrasound. The fourth patient undergoes CT vascular imaging of the thorax to evaluate the widened mediastinum.
Stable patients can safely undergo cross-sectional imaging to precisely diagnose and grade injuries, potentially avoiding unnecessary operations.

Key Concept

The Advanced Trauma Life Support (ATLS) algorithm relies heavily on hemodynamic stability to guide the choice between immediate surgical/angiographic intervention and advanced diagnostic imaging.
Question 1598Question →

Evaluate the following patient presentations involving esophageal symptoms. Match each specific clinical vignette to the highly characteristic diagnostic finding associated with the underlying pathology.

Click a left item, then click its matching right item

Items

A 35-year-old woman presents with progressive dysphagia to both solids and liquids, frequent regurgitation of undigested food, and a 5-kg (11-lb) weight loss over the past year.
A 52-year-old man presents with recurrent, severe retrosternal chest pain that occasionally radiates to the jaw. Extensive cardiac evaluation is unremarkable. He notes intermittent difficulty swallowing hot and cold liquids.
A 45-year-old woman with a history of Raynaud phenomenon presents with refractory gastroesophageal reflux symptoms and progressive dysphagia. Physical examination reveals thickened, tight skin over her fingers.
A 28-year-old man with allergic rhinitis and atopic dermatitis presents to the emergency department with acute meat impaction. He reports a long-standing history of dysphagia exclusively to solid foods.

Matches

Show answer & explanation

Answer

Achalasia pairs with aperistalsis and incomplete LES relaxation; Diffuse esophageal spasm pairs with simultaneous contractions and normal LES relaxation; Scleroderma pairs with absent distal peristalsis and a hypotensive LES; Eosinophilic esophagitis pairs with >15 eosinophils/HPF on biopsy.
Each clinical vignette provides specific clues pointing to a distinct esophageal pathology. Achalasia presents with progressive solid and liquid dysphagia due to myenteric plexus degeneration, confirmed by aperistalsis and incomplete LES relaxation on manometry. Diffuse esophageal spasm causes non-cardiac chest pain and is diagnosed by premature, uncoordinated contractions with a normally relaxing LES. Scleroderma esophagus results from smooth muscle fibrosis, leading to an incompetent LES (severe GERD) and absent distal peristalsis. Eosinophilic esophagitis classically affects young men with atopy, causing solid food dysphagia and food impaction, diagnosed by >15 eosinophils/HPF on mucosal biopsy.

Step-by-Step Solution

1
Analyze the first vignette: a 35-year-old woman with progressive dysphagia to both solids and liquids, regurgitation, and weight loss.
This presentation is classic for a primary motility disorder, specifically achalasia.
Achalasia involves the loss of inhibitory ganglion cells, which requires matching with the manometry finding of aperistalsis and incomplete LES relaxation.
2
Evaluate the second vignette: a 52-year-old man with non-cardiac chest pain and intermittent dysphagia to hot/cold liquids.
This episodic presentation strongly suggests diffuse esophageal spasm (DES).
DES is characterized by uncoordinated smooth muscle hyperactivity; match it with the manometry finding showing premature, simultaneous contractions but normal LES relaxation.
3
Review the third vignette: a 45-year-old woman with refractory GERD, Raynaud phenomenon, and sclerodactyly.
The systemic findings point to systemic sclerosis (scleroderma) involving the esophagus.
Scleroderma causes fibrosis of the smooth muscle layer. This corresponds to the manometry finding of absent distal peristalsis and a profoundly hypotensive LES.
4
Examine the fourth vignette: a 28-year-old man with atopy presenting with acute food impaction and solid-only dysphagia.
This is the pathognomonic presentation for eosinophilic esophagitis (EoE).
Unlike primary motility disorders, EoE is a mucosal inflammatory condition diagnosed via biopsy; match it with the finding of >15 intraepithelial eosinophils per high-power field.

Key Concept

Differentiation of esophageal dysphagia syndromes utilizing clinical presentation, high-resolution manometry, and histopathology.
Question 1599Question →

Match each clinical presentation of systemic vasculitis with its most likely corresponding diagnosis.

Click a left item, then click its matching right item

Items

Adult-onset asthma, chronic rhinosinusitis, peripheral neuropathy (mononeuritis multiplex), and laboratory findings showing marked eosinophilia.
Chronic otitis media, refractory sinusitis, hemoptysis from cavitary lung lesions, and a urinalysis demonstrating red blood cell casts.
Recurrent postprandial abdominal pain, testicular pain, new-onset foot drop, and angiographic demonstration of renal microaneurysms without lung involvement.
Recurrent episodes of palpable purpura on the lower extremities, severe arthralgias, and laboratory studies revealing profoundly low C4 levels.

Matches

Show answer & explanation

Answer

The correct matches rely on identifying the unique organ involvement and laboratory hallmarks of each vasculitis: asthma and eosinophilia match with Eosinophilic granulomatosis with polyangiitis; cavitary lung lesions and glomerulonephritis match with Granulomatosis with polyangiitis; medium-vessel involvement sparing the lungs matches with Polyarteritis nodosa; and palpable purpura with low C4 matches with Cryoglobulinemic vasculitis.
Each systemic vasculitis exhibits a distinct pattern: EGPA features atopy and eosinophilia; GPA features necrotizing upper/lower respiratory granulomas and glomerulonephritis; PAN is a medium-vessel disease sparing the lungs; and Cryoglobulinemic vasculitis is a small-vessel immune complex disease marked by low C4 and purpura.

Step-by-Step Solution

1
Analyze the size of the vessels involved and the specific organs affected in each clinical vignette.
Identified small-vessel patterns (pulmonary-renal syndromes, purpura) and a medium-vessel pattern (microaneurysms, sparing of lungs).
Vasculitides are broadly classified by the size of the predominant blood vessels they affect, which determines their clinical presentation.
2
Differentiate between the ANCA-associated small vessel vasculitides (AAVs).
The presence of adult-onset asthma and eosinophilia points exclusively to Eosinophilic granulomatosis with polyangiitis, while upper/lower destructive respiratory lesions combined with renal disease point to Granulomatosis with polyangiitis.
Although GPA, EGPA, and Microscopic polyangiitis all affect small vessels and kidneys, their pulmonary and systemic features are highly distinct.
3
Identify the remaining conditions by their classic risk factors and laboratory markers.
Microaneurysms and visceral ischemia indicate Polyarteritis nodosa, while palpable purpura and low C4 indicate Cryoglobulinemic vasculitis.
Complement consumption (low C4) is a hallmark of cryoglobulinemia, whereas angiographic evidence of aneurysms is the gold standard for diagnosing PAN.

Key Concept

Clinical differentiation of systemic vasculitides based on classic symptom triads, organ involvement, and serologic markers.
Question 1600Question →

A reproductive endocrinology clinic is evaluating four male patients for primary infertility. Each patient has confirmed azoospermia on semen analysis but presents with a distinct endocrine laboratory profile and specific physical examination findings. Match the following clinical and laboratory profiles with their most likely underlying etiology.

Click a left item, then click its matching right item

Items

Azoospermia, decreased serum FSH and LH, decreased serum testosterone, anosmia
Azoospermia, elevated serum FSH and LH, decreased serum testosterone, small firm testes
Azoospermia, normal serum FSH and LH, normal serum testosterone, nonpalpable vas deferens
Azoospermia, decreased serum FSH and LH, elevated serum testosterone, muscular hypertrophy and testicular atrophy

Matches

Show answer & explanation

Answer

The profile with low FSH/LH, low testosterone, and anosmia matches Kallmann syndrome. The profile with high FSH/LH, low testosterone, and small testes matches Klinefelter syndrome. The profile with normal labs and nonpalpable vas deferens matches Cystic fibrosis. The profile with low FSH/LH, high testosterone, and testicular atrophy matches Exogenous anabolic steroid use.
Kallmann syndrome presents with hypogonadotropic hypogonadism and anosmia due to failed neuronal migration. Klinefelter syndrome presents with hypergonadotropic hypogonadism and small firm testes due to primary gonadal failure. CFTR mutations cause obstructive azoospermia with normal endocrine labs. Exogenous steroids suppress gonadotropins while maintaining high systemic androgens, leading to testicular atrophy.

Step-by-Step Solution

1
Analyze gonadotropin (FSH/LH) and testosterone levels to determine the level of the defect.
Low FSH/LH with low testosterone indicates central (hypogonadotropic) hypogonadism. High FSH/LH with low testosterone indicates primary (hypergonadotropic) testicular failure. Normal labs suggest an obstructive cause. Low FSH/LH with high testosterone suggests exogenous suppression.
Categorizing the endocrine axis distinguishes between hypothalamic/pituitary disorders, primary gonadal failure, obstructive pathology, and external negative feedback.
2
Correlate the endocrine categories with physical examination findings.
Central hypogonadism with anosmia points to Kallmann syndrome. Primary testicular failure with small firm testes points to Klinefelter syndrome. Obstructive azoospermia with an absent vas deferens is characteristic of Cystic fibrosis. Exogenous suppression with testicular atrophy points to anabolic steroids.
Physical findings provide the specific diagnosis within the broader endocrine category.

Key Concept

Male factor infertility workup requires distinguishing between pre-testicular (hypogonadotropic), testicular (hypergonadotropic), and post-testicular (obstructive) etiologies using FSH, LH, and testosterone levels in conjunction with physical examination.
PreviousPage 80 / 93Next
All practice questions — USMLE Step 2 CK | Examkin