Internal Medicine

An 18-year-old female university student is evaluated in the emergency department after her roommate found her to be acutely disoriented. Over the last 12 hours, the patient has experienced continuous nausea, episodes of vomiting, and a persistent buzzing sensation in her ears. The roommate suspects she ingested a large quantity of an over-the-counter medication following a personal dispute. Her temperature is $37.8^\circ C$ ($100^\circ F$), blood pressure is $114/72$ mm Hg, pulse is $118$/min, and respirations are $26$/min. Physical examination shows a diaphoretic, agitated young woman with deep, rapid breathing.

Laboratory results are as follows:

Which of the following best describes this patient's underlying acid-base disturbance?

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.

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 ($\Delta AG / \Delta HCO_3^-$)?

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?

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?

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

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

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.

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?

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?

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:

Arterial blood gas (room air):

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?

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:

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.

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.

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

Match each patient's clinical presentation with the most likely predominant finding on their peripheral blood smear.

A $68$-year-old man is hospitalized due to a $4$-week history of fatigue, intermittent fevers, and unintentional weight loss. Two months ago, he underwent a cystoscopy for evaluation of hematuria. His temperature is $38.2^\circ\text{C}$ ($100.8^\circ\text{F}$), pulse is $92/\text{min}$, and blood pressure is $118/74\text{ mm Hg}$. Physical examination reveals small, linear, dark red streaks in the nail beds of both hands and a new grade $3/6$ holosystolic murmur heard best at the cardiac apex.

Echocardiography demonstrates a $1.2\text{-cm}$ mobile vegetation on the mitral valve with moderate mitral regurgitation.

Laboratory studies show:
Leukocyte count: $14,500/\text{mm}^3$
Serum creatinine: $2.2\text{ mg/dL}$ (baseline: $1.0\text{ mg/dL}$)

Three sets of blood cultures are drawn, and the patient is started empirically on intravenous vancomycin and piperacillin-tazobactam. Forty-eight hours later, all blood culture bottles grow *Enterococcus faecalis*. Susceptibility testing reveals:

Ampicillin: Susceptible
Vancomycin: Susceptible
Piperacillin-tazobactam: Susceptible
Gentamicin: High-level resistance

Which of the following is the most appropriate targeted pharmacotherapy for this patient?

An evaluation is requested for a 32-year-old woman who reports profound fatigue, cold intolerance, and a $5$-kg ($11$-lb) weight gain over the past six months. She also notes that her menstrual cycles have not resumed since the vaginal delivery of her first child 10 months ago. The patient's medical records indicate that her delivery was complicated by uterine atony and severe postpartum hemorrhage requiring the transfusion of four units of packed red blood cells. Following the birth, she was unable to breastfeed despite multiple attempts.

Vital signs include a blood pressure of $88/56$ mm Hg and a heart rate of $58$/min. Physical examination demonstrates pale, dry skin and a noticeable loss of axillary and pubic hair. Deep tendon reflexes show delayed relaxation.

Laboratory studies reveal:
Thyroid-stimulating hormone (TSH): $1.3$ $\mu$ U/mL (Normal: $0.5$-$5.0$ $\mu$ U/mL)
Free thyroxine (T4): $0.4$ 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 $54$-year-old woman arrives at the emergency department with severe, sudden-onset breathing difficulty that started one hour ago. The patient has a history of long-standing hypertension but has not taken her prescribed medications for several months.

On evaluation, she is sitting upright, diaphoretic, and in significant respiratory distress.

Vital signs show a temperature of $37.0^\circ\text{C}$ ($98.6^\circ\text{F}$), blood pressure of $220/115\text{ mm Hg}$, heart rate of $118/\text{min}$, and respiratory rate of $28/\text{min}$. Oxygen saturation is $88\%$ on room air.

Physical examination reveals prominent jugular venous distention. Pulmonary auscultation demonstrates bilateral crackles extending to the apices and widespread expiratory wheezing.

Cardiac auscultation reveals a regular tachycardia and a prominent fourth heart sound (S4). There is no peripheral edema.

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

Match each physical examination finding and its corresponding response to dynamic auscultatory maneuvers with the most likely underlying structural or valvular pathology.

A 34-year-old man with a history of intravenous opioid use disorder is hospitalized for a 1-week history of fever, chills, and pleuritic chest pain. On admission, multiple sets of blood cultures are drawn, and empiric intravenous vancomycin and cefepime are initiated. A transthoracic echocardiogram reveals a $1.4\text{-cm}$ mobile vegetation on the tricuspid valve with moderate tricuspid regurgitation. Two days later, all blood culture bottles grow *Staphylococcus aureus*. Susceptibility testing indicates the isolate is resistant to penicillin G, but susceptible to oxacillin, cefazolin, and vancomycin. The patient's medical record notes a history of a diffuse maculopapular rash after taking amoxicillin for a respiratory infection 5 years ago; he specifically denies any history of facial swelling, difficulty breathing, or anaphylaxis associated with medications. His temperature is currently $37.6^\circ\text{C}$ ($99.7^\circ\text{F}$), blood pressure is $122/76\text{ mm Hg}$, and heart rate is $82/\text{min}$. Which of the following is the most appropriate next step in the pharmacologic management of this patient?

A patient with a fifty-pack-year smoking history and severe chronic obstructive pulmonary disease comes to the clinic for a routine follow-up. He is seventy-two years old and reports progressively worsening fatigue, bilateral leg swelling, and right upper quadrant abdominal discomfort over the past few months. His current medications include a long-acting muscarinic antagonist and an inhaled corticosteroid. Vital signs show a respiratory rate of $22$/min and an oxygen saturation of $87\%$ on room air. Physical examination reveals elevated jugular venous pressure, a right ventricular heave, and $2+$ pitting edema of the lower extremities up to the knees. Auscultation of the heart reveals a loud $P_2$. Lung auscultation shows decreased breath sounds globally without wheezes. Which of the following interventions is most likely to improve long-term survival in this patient?