Internal Medicine

Match each clinical and laboratory profile of hypokalemic metabolic alkalosis to its most likely underlying etiology.

A 28-year-old daycare worker comes to the urgent care center complaining of severe, watery diarrhea for the past four days. She reports drinking only tap water since her symptoms began and has been unable to keep solid food down. On physical examination, her blood pressure is 105/65 mmHg and her pulse is 112/min. Her mucous membranes are dry. Laboratory studies show:

Which of the following is the expected arterial partial pressure of carbon dioxide ($PaCO_2$) for this patient if appropriate respiratory compensation has occurred?

Match each classic urinalysis sediment finding with the renal pathology it most strongly indicates.

Emergency medical services bring a 61-year-old man to the emergency department after his family found him confused and febrile. His wife reports that he complained of a severe, throbbing headache yesterday before becoming progressively somnolent this morning. His past medical history includes hypertension and type 2 diabetes mellitus. Temperature is $39.4^{\circ}\text{C}$ ($102.9^{\circ}\text{F}$), blood pressure is $138/86\text{ mmHg}$, pulse is $112/\text{min}$, and respirations are $18/\text{min}$. On physical examination, the patient is lethargic and oriented only to person. He strongly resists passive neck flexion. Fundoscopic examination reveals bilateral blurring of the optic disc margins. Neurologic examination demonstrates a left-sided facial droop and decreased strength in the left upper extremity compared to the right. Arrange the following steps in the most appropriate chronological order for managing this patient.

A 28-year-old woman is brought to the emergency department due to a 5-day history of extreme fatigue, easy bruising, and spontaneous gingival bleeding. She has no significant past medical history. Her temperature is 37.9°C (100.2°F), blood pressure is 105/65 mmHg, and pulse is 112/min. Physical examination reveals diffuse petechiae across her trunk and extremities, as well as oozing from a recent venipuncture site. Laboratory studies show:

A peripheral blood smear demonstrates numerous atypical promyelocytes containing abundant azurophilic granules and multiple Auer rods.

Arrange the following steps in the most appropriate chronological sequence for the management of this patient.

A $68$-year-old man is evaluated in the hospital on the third day of an admission for community-acquired pneumonia. At the time of admission, he had a fever, productive cough, and a right lower lobe infiltrate on chest radiograph. He was started on empiric therapy with intravenous ceftriaxone and azithromycin. Sputum Gram stain and culture were obtained prior to the administration of antibiotics.

Currently, the patient feels much better. His temperature is $37.1^\circ\text{C}$ ($98.8^\circ\text{F}$), blood pressure is $124/78\text{ mm Hg}$, pulse is $76/\text{min}$, and respirations are $16/\text{min}$. Oxygen saturation is $96\%$ on room air. He is tolerating a regular diet.

Sputum culture has grown heavy *Streptococcus pneumoniae*. Antimicrobial susceptibility testing of the isolate shows the following:

The patient is ready for discharge to home. Which of the following is the most appropriate antibiotic regimen to prescribe for this patient upon discharge?

A 21-year-old male is brought to the emergency department by his roommate due to profound generalized weakness and episodes of confusion over the past 24 hours. The roommate mentions the patient was recently fired from his job at a paint manufacturing plant and has been spending most of his time locked in his room with a strong, unusual chemical odor. On physical examination, the patient is lethargic but arousable. Muscle strength is 2/5 in the bilateral lower extremities and 3/5 in the upper extremities. Deep tendon reflexes are diminished. His blood pressure is 110/70 mm Hg, heart rate is 98/min, and respiratory rate is 22/min.

Laboratory studies reveal the following:

Arterial blood gas on room air shows a pH of 7.28 and a $pCO_2$ of 26 mm Hg. Urinalysis reveals a pH of 6.8 with no protein or blood. Urine electrolyte testing reveals a sodium of 45 mEq/L, potassium of 25 mEq/L, and chloride of 30 mEq/L.

Which of the following is the most likely primary mechanism responsible for this patient's laboratory abnormalities?

A 24-year-old woman comes to the emergency department because she has noticed a new rash on her legs and bleeding from her gums when she brushes her teeth over the past 3 days. She feels otherwise well and reports no fever, weight loss, joint pain, or recent illnesses. She has no significant past medical history and takes no medications. Vital signs are within normal limits. Physical examination reveals scattered, non-blanching, pinpoint red macules over her bilateral lower extremities and small purpura on her buccal mucosa. There is no jaundice, lymphadenopathy, or hepatosplenomegaly.

Laboratory studies show:
Hemoglobin: 13.2 g/dL
Leukocyte count: 7,500/mm³
Platelet count: 12,000/mm³
Prothrombin time (PT): 11 seconds
Activated partial thromboplastin time (aPTT): 30 seconds

A peripheral blood smear reveals enlarged platelets but is otherwise unremarkable, with no fragmented red blood cells or blasts seen.

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

A 45-year-old man is evaluated for resistant hypertension. His blood pressure is 168/102 mmHg despite adherence to maximum tolerated doses of amlodipine, lisinopril, and doxazosin. Laboratory evaluation reveals a serum potassium of 3.1 mEq/L. Arrange the following steps in the correct diagnostic and management sequence for evaluating and treating this patient's most likely condition.

A 28-year-old woman with untreated Graves disease is brought to the emergency department due to confusion, severe agitation, and a temperature of 39.4°C (103°F). Her heart rate is 145/min and blood pressure is 150/70 mm Hg. Physical examination reveals severe diaphoresis, a fine tremor, and a diffusely enlarged thyroid gland. She is diagnosed with a thyroid storm. Arrange the following management steps in the correct chronological sequence to safely and effectively treat this patient's condition.

A $48$-year-old man comes to the clinic reporting a $6$-month history of progressive fatigue, generalized weakness, and severe cold intolerance. He also mentions decreased libido, occasional morning headaches, and a recent incident where he injured his shoulder because he "did not see the door frame." He takes no medications. Vital signs show a blood pressure of $94/62$ mm Hg while sitting and $82/50$ mm Hg upon standing. His heart rate is $58$/min. Physical examination reveals pale skin, a delayed relaxation phase of the Achilles deep tendon reflexes, and sparse axillary and pubic hair. Visual field testing by confrontation demonstrates bilateral temporal deficits. Laboratory studies show:

* Serum sodium: $132$ mEq/L
* Serum potassium: $4.2$ mEq/L
* Thyroid-stimulating hormone (TSH): $1.8$ $\mu$ U/mL (Normal: $0.5$-$5.0$ $\mu$ U/mL)
* Free thyroxine (T4): $0.5$ ng/dL (Normal: $0.9$-$1.7$ ng/dL)

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

A 42-year-old man is evaluated in the hospital for ongoing management of right knee septic arthritis. He originally presented 3 days ago with an acutely painful, swollen right knee and a temperature of 38.8°C (101.8°F). Initial arthrocentesis revealed purulent synovial fluid with 95,000 leukocytes/mm³, and a Gram stain demonstrated Gram-positive cocci in clusters. He underwent prompt arthroscopic irrigation and debridement, and was empirically started on intravenous vancomycin. Today, the patient reports feeling much better, his knee pain has decreased, and he has been afebrile for 24 hours. Final synovial fluid cultures are positive for Staphylococcus aureus. Antimicrobial susceptibility testing shows that the isolate is resistant to penicillin but susceptible to oxacillin, cefazolin, clindamycin, and vancomycin. Which of the following is the most appropriate next step in the antibiotic management of this patient?

A 42-year-old woman presents to the emergency department with a 2-day history of profound, generalized muscle weakness. She has a past medical history of rheumatoid arthritis and complains of chronic dry eyes and a dry mouth. She takes no daily medications. Her blood pressure is 118/76 mm Hg, heart rate is 88/min, and respiratory rate is 18/min. Physical examination reveals normal muscle bulk but symmetrically decreased proximal and distal muscle strength (3/5) in both the upper and lower extremities. Deep tendon reflexes are globally diminished. Laboratory evaluation reveals the following:

Serum chemistry:
Sodium: 139 mEq/L
Potassium: 2.1 mEq/L
Chloride: 114 mEq/L
Bicarbonate: 14 mEq/L
Blood urea nitrogen: 14 mg/dL
Creatinine: 0.9 mg/dL

Arterial blood gas (room air):
pH: 7.28
pCO2: 30 mm Hg
pO2: 95 mm Hg

Urinalysis:
pH: 6.8
Specific gravity: 1.015
Protein: Negative
Glucose: Negative
Ketones: Negative

Which of the following is the primary pathophysiologic mechanism underlying this patient's laboratory abnormalities?

A 45-year-old woman comes to the clinic reporting progressive fatigue, generalized weakness, and constipation over the past 4 months. She also reports a $4\text{-kg}$ ($8.8\text{-lb}$) weight gain during this time despite a decreased appetite. Her menstrual periods have been absent for the past 6 months. Her only medication is a levonorgestrel-releasing intrauterine device. Blood pressure is $105/65\text{ mm Hg}$, and pulse is $58\text{/min}$. Physical examination shows dry skin and delayed relaxation of the deep tendon reflexes. Visual fields are full to confrontation. Laboratory studies show:

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

A 55-year-old man is brought to the emergency department by his daughter due to severe weakness, nausea, and abdominal pain for the past 2 days. He also reports mild shortness of breath. His medical history includes chronic obstructive pulmonary disease (COPD) and a nonfunctioning pituitary macroadenoma treated with transsphenoidal resection 3 years ago. He has been noncompliant with all his prescribed medications for the last month.

Vital signs are temperature 37.8°C (100.0°F), blood pressure 82/50 mm Hg (which decreases to 72/40 mm Hg upon sitting), heart rate 116/min, and respiratory rate 22/min. Physical examination reveals dry mucous membranes and poor skin turgor. Pulmonary auscultation reveals prolonged expiration and scattered end-expiratory wheezes bilaterally, without crackles or jugular venous distension.

Laboratory studies show:

A chest radiograph shows mild hyperinflation but no focal infiltrates, cardiomegaly, or pulmonary edema. The patient receives 3 liters of intravenous normal saline over 2 hours, but his blood pressure remains 84/52 mm Hg.

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

A 71-year-old man is brought to the emergency department with altered mental status, fever, and suprapubic pain. His temperature is 39.4°C (102.9°F), blood pressure is 86/52 mm Hg, pulse is 122/min, and respirations are 24/min. Initial laboratory results show a leukocyte count of 19,200/mm³ and a serum creatinine of 1.8 mg/dL (baseline 1.1 mg/dL). Urinalysis reveals numerous leukocytes, positive nitrites, and bacteria. He is diagnosed with a complicated urinary tract infection and suspected urosepsis.

Arrange the following management steps in the correct chronological order, prioritizing acute stabilization and adhering to current principles of antimicrobial stewardship.

A $22$-year-old man with type 1 diabetes mellitus is brought to the emergency department with nausea, vomiting, generalized weakness, and confusion. Vital signs show blood pressure $90/60 \text{ mmHg}$, heart rate $122 \text{/min}$, and respirations $28 \text{/min}$ (deep and rapid). Fingerstick glucose is $550 \text{ mg/dL}$. Laboratory results show:

Sodium: $132 \text{ mEq/L}$
Potassium: $3.1 \text{ mEq/L}$
Chloride: $98 \text{ mEq/L}$
Bicarbonate: $10 \text{ mEq/L}$
BUN: $32 \text{ mg/dL}$
Creatinine: $1.4 \text{ mg/dL}$
Arterial pH: $7.15$
Urine ketones: Large

Arrange the following steps in the most appropriate chronological sequence for the immediate and subsequent management of this patient's diabetic ketoacidosis.

A 38-year-old woman is evaluated in the outpatient clinic for generalized weakness, unremitting fatigue, and the absence of menstruation for the past 7 months. She also notes a spontaneous, bilateral milky discharge from her breasts. The patient has no prior medical conditions, takes no prescription medications, and a recent home pregnancy test was negative. Blood pressure is 110/70 mm Hg and pulse is 54/min. Physical examination reveals delayed relaxation of the deep tendon reflexes and pale conjunctivae. Visual field testing is normal.

Laboratory evaluation shows the following:

Which of the following is the most likely pathophysiologic mechanism explaining this patient's findings?

A 45-year-old man comes to the emergency department reporting four days of frequent, large-volume watery stools. He feels weak and lightheaded when standing. Physical examination reveals dry mucous membranes, flat neck veins, and delayed capillary refill. Laboratory results are as follows:

Based on these findings, which of the following best describes this patient's primary acid-base disorder?

Match each set of laboratory findings with the most likely underlying etiology. Assume all patients are normotensive adults who are not currently taking any prescription medications.