Internal Medicine

Match each clinical presentation with the most appropriate first-line targeted or empiric antimicrobial therapy.

A $32$-year-old man comes to the clinic to establish care after recently testing positive for human immunodeficiency virus (HIV). He is currently asymptomatic and has no history of opportunistic infections. Vital signs are within normal limits. Physical examination reveals no lymphadenopathy, oral thrush, or skin lesions. Laboratory evaluation shows a CD4 T-lymphocyte count of $38/\mu\text{L}$ and an HIV RNA viral load of $280,000$ copies/mL. Serologic testing is positive for *Toxoplasma gondii* IgG antibodies. An interferon-gamma release assay is negative. An antiretroviral therapy (ART) regimen consisting of bictegravir, emtricitabine, and tenofovir alafenamide is initiated today. In addition to ART, which of the following is the most appropriate prophylactic antimicrobial regimen for this patient?

A 50-year-old male presents to the outpatient clinic reporting progressive weakness and a metallic taste in his mouth over the last several weeks. He has a 15-year history of poorly controlled hypertension. His blood pressure is $165/95 \text{ mm Hg}$, pulse is $84/\text{min}$, and respiratory rate is $22/\text{min}$. Physical examination reveals trace bilateral lower extremity edema and a pale complexion. Laboratory studies are obtained and reveal the following:

Serum chemistry:
$Na^+$: $140 \text{ mEq/L}$
$K^+$: $5.2 \text{ mEq/L}$
$Cl^-$: $102 \text{ mEq/L}$
$HCO_3^-$: $12 \text{ mEq/L}$
Blood urea nitrogen: $85 \text{ mg/dL}$
Serum creatinine: $5.5 \text{ mg/dL}$

Arterial blood gas (room air):
pH: $7.25$
$pCO_2$: $26 \text{ mm Hg}$
$pO_2$: $95 \text{ mm Hg}$

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

An executive health screening is performed for a 45-year-old man who reports a 6-month history of significant fatigue, reduced libido, and a constant feeling of coldness. Physical examination shows a heart rate of $56/min$, normal blood pressure, and delayed relaxation of the deep tendon reflexes. Laboratory evaluation reveals:

Thyroid-stimulating hormone (TSH): $1.1 \mu U/mL$ (Normal: $0.4 - 4.0 \mu U/mL$)
Free thyroxine (T4): $0.4 ng/dL$ (Normal: $0.9 - 1.7 ng/dL$)

Which of the following additional findings is most likely to be present in this patient?

A 58-year-old woman is brought to the emergency department due to a 1-day history of fever, chills, and progressive shortness of breath. She completed her second cycle of systemic chemotherapy (docetaxel and cyclophosphamide) for node-positive breast cancer 8 days ago. Medical history is significant for ischemic cardiomyopathy (left ventricular ejection fraction 40%) and moderate chronic obstructive pulmonary disease. Her temperature is 38.9°C (102.0°F), blood pressure is 84/54 mm Hg, pulse is 118/min, and respirations are 24/min. Pulse oximetry shows 91% on room air. The patient appears lethargic. Jugular venous pressure is 6 cm H2O. Lung auscultation reveals crackles in the right lower lung base. Heart sounds are rapid but regular, with no S3 gallop. The extremities are warm to the touch. Laboratory results are as follows:

Hemoglobin: 9.8 g/dL
Leukocyte count: $600/\mu L$
Absolute neutrophil count: $120/\mu L$
Platelet count: $110,000/\mu L$
Creatinine: 1.4 mg/dL
Thyroid-stimulating hormone (TSH): $0.4\ \mu U/mL$
Free T4: $0.9\ ng/dL$

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

For each clinical presentation described below, select the most appropriate initial antimicrobial agent according to current guidelines.

A 42-year-old woman is diagnosed with severe, seropositive rheumatoid arthritis characterized by symmetric polyarthritis involving the metacarpophalangeal joints, morning stiffness lasting 2 hours, and bone erosions on radiography. She is preparing to begin long-term pharmacotherapy. Arrange the following clinical steps in the correct chronological sequence according to current consensus guidelines for the escalating management of rheumatoid arthritis.

A $34$-year-old woman is evaluated in the emergency department for a $2$-day history of heavy gingival bleeding, recurrent epistaxis, and a large bruise on her thigh after minor trauma. Her temperature is $37.9^\circ\text{C}$ ($100.2^\circ\text{F}$), pulse is $112/\text{min}$, and blood pressure is $105/65 \text{ mm Hg}$. Physical examination reveals pallor, diffuse petechiae over the chest and extremities, and continuous oozing of blood from the intravenous line insertion site. Laboratory studies show:

A peripheral blood smear demonstrates numerous atypical mononuclear cells with folded nuclei, heavily granulated cytoplasm, and bundles of rod-shaped cytoplasmic inclusions.

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

Match each clinical presentation with the most likely corresponding serum and urine laboratory findings.

Match each patient's clinical presentation with the primary pathophysiologic mechanism or underlying diagnosis responsible for their electrolyte and acid-base disturbances.

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

An 18-year-old male with homozygous sickle cell disease is brought to the emergency department due to a two-day history of progressively worsening chest pain, productive cough, and subjective fevers. Initial vital signs show a temperature of 38.8°C (101.8°F), blood pressure of 118/76 mm Hg, heart rate of 112/min, and respiratory rate of 26/min. Pulse oximetry reveals an oxygen saturation of 87% on room air. Physical examination is notable for scleral icterus and decreased breath sounds with crackles over the right lower lung fields. Laboratory evaluation demonstrates a hemoglobin of 7.2 g/dL, leukocyte count of 16,500/mm³, and reticulocyte count of 12%. A chest radiograph reveals a new consolidation in the right lower lobe.

What is the most appropriate chronological sequence for the management of this patient's condition?

An otherwise healthy 42-year-old male is evaluated in the ambulatory care center due to a painful swelling on his right thigh. The lesion has been progressively enlarging over the past three days. He takes no medications and has no significant past medical history. Vital signs demonstrate a temperature of 37.1°C (98.8°F), blood pressure of 122/78 mm Hg, and a heart rate of 74/min. Physical examination of the right anterior thigh reveals a 3-cm, highly tender, fluctuant, erythematous nodule with a central purulent punctum. There is no significant surrounding induration, and no regional lymphadenopathy is appreciated. Which of the following is the most appropriate next step in management?

An 18-year-old female gymnast is brought to the university health clinic by her roommate. She has been vomiting persistently for the past four days. The roommate mentions she has observed similar episodes in the past, though not this severe. Physical examination shows dry mucous membranes, poor skin turgor, and a pulse of 112/min.

Laboratory studies show the following:
- $Na^+$: 139 mEq/L
- $K^+$: 2.9 mEq/L
- $Cl^-$: 94 mEq/L
- $HCO_3^-$: 36 mEq/L

Arterial blood gas analysis on room air reveals:
- pH: 7.52
- $pCO_2$: 48 mm Hg
- $pO_2$: 94 mm Hg

Based on these findings, which of the following best characterizes this patient's acid-base status?

A 19-year-old man with type 1 diabetes mellitus is brought to the emergency department due to lethargy, deep and rapid breathing, and a fruity breath odor. Laboratory results show a blood glucose of $580 \text{ mg/dL}$, arterial pH of $7.12$, serum bicarbonate of $10 \text{ mEq/L}$, and a serum potassium of $5.6 \text{ mEq/L}$. He is diagnosed with severe diabetic ketoacidosis (DKA).

Arrange the following management steps in the optimal chronological sequence for this patient.

A $62$-year-old man with poorly controlled type 2 diabetes mellitus is admitted to the hospital with a non-healing ulcer on the plantar aspect of his right foot. The ulcer is surrounded by $4$ cm of erythema and warmth. During physical examination, a sterile metal probe easily reaches the underlying bone. His temperature is $38.2^\circ\text{C}$ ($100.8^\circ\text{F}$), blood pressure is $130/80$ mm Hg, and pulse is $96$/min. Laboratory studies show a leukocyte count of $14,500/\text{mm}^3$. He is started on empiric intravenous vancomycin and piperacillin-tazobactam. A bone biopsy is performed on the second day of admission. By day $5$, his fever has resolved, and the erythema has significantly decreased. The bone biopsy cultures grow only Staphylococcus aureus, which is sensitive to oxacillin, cefazolin, and clindamycin, but resistant to penicillin. No Gram-negative bacilli or anaerobes are isolated. Which of the following is the most appropriate next step in pharmacotherapy?

A female university student in her early $20$ s is evaluated in the rheumatology clinic for a $6$-week history of profound fatigue and stiffness in her proximal interphalangeal joints. She notes that the skin across her cheeks becomes persistently red and painful after brief sun exposure. Over the past $14$ days, she has developed noticeable bilateral ankle swelling. Her blood pressure is $145/92$ mmHg. Laboratory evaluation shows a serum creatinine of $1.4$ mg/dL, and urinalysis demonstrates $3+$ proteinuria with red blood cell casts. Arrange the following clinical interventions in the standard chronological sequence for the definitive diagnostic workup and targeted management of this patient's underlying condition.

Match the following classic urinalysis sediment findings with the most appropriate renal pathology or clinical syndrome.

A 45-year-old man is evaluated for treatment-resistant hypertension. His blood pressure remains consistently greater than 150/90 mm Hg despite documented compliance with a three-drug antihypertensive regimen that includes a thiazide diuretic. Recent laboratory testing revealed unprovoked hypokalemia with a serum potassium level of 2.9 mEq/L. The physician strongly suspects primary hyperaldosteronism and plans a complete diagnostic workup to determine if the patient is a candidate for surgical cure. Arrange the following diagnostic and management steps in the most appropriate chronological sequence for the evaluation of this patient.

A 26-year-old male athlete undergoes an independent medical evaluation required for a specialized life insurance policy. He reports feeling exceptionally well and currently runs approximately $30\text{ miles}$ per week. His family history is notable for a younger brother diagnosed with attention-deficit/hyperactivity disorder, but there is no known history of autoimmune or endocrine diseases.

Vital signs include a heart rate of $64\text{/min}$ and a blood pressure of $118/74\text{ mm Hg}$. Physical examination reveals a normal-sized, non-tender thyroid gland without palpable nodules. There is no evidence of proptosis, lid lag, hyperreflexia, or resting tremor.

Laboratory studies demonstrate:

An MRI of the brain with gadolinium contrast demonstrates a normal pituitary gland without sellar or suprasellar masses.

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