A 62-year-old woman with a 10-year history of diffuse cutaneous systemic sclerosis present… — USMLE Step 2 CK

A 62-year-old woman with a 10-year history of diffuse cutaneous systemic sclerosis presents to the emergency department with acute-onset shortness of breath and profound fatigue over the last 48 hours. Her medical history includes Raynaud phenomenon, gastroesophageal reflux disease, and mild interstitial lung disease. Her baseline medications include mycophenolate mofetil, omeprazole, and nifedipine. Three weeks ago, she was evaluated by an outside provider for worsening polyarticular joint pain and was started on oral prednisone $60\text{ mg}$ daily.

On physical examination, her temperature is $37.6^\circ\text{C}$ ( $99.7^\circ\text{F}$ ), blood pressure is $225/115\text{ mmHg}$ , heart rate is $110/\text{min}$ , and respiratory rate is $26/\text{min}$ . Pulse oximetry is $92\%$ on room air. Jugular venous distention is present. Pulmonary auscultation reveals bilateral basilar crackles.

Laboratory results are as follows:

Test	Result	Reference Range
Hemoglobin	$8.2\text{ g/dL}$	$12.0-15.5\text{ g/dL}$
Platelets	$85,000/\text{mm}^3$	$150,000-400,000/\text{mm}^3$
Leukocytes	$9,500/\text{mm}^3$	$4,500-11,000/\text{mm}^3$
Blood urea nitrogen	$52\text{ mg/dL}$	$7-20\text{ mg/dL}$
Creatinine	$3.4\text{ mg/dL}$	$0.6-1.1\text{ mg/dL}$
Thyroid-stimulating hormone (TSH)	$0.2\text{ }\mu\text{U/mL}$	$0.4-4.0\text{ }\mu\text{U/mL}$
Free T4	$1.2\text{ ng/dL}$	$0.9-1.7\text{ ng/dL}$

Arterial blood gas on room air:

Test	Result
pH	$7.32$
pCO2	$30\text{ mmHg}$
pO2	$65\text{ mmHg}$
HCO3	$15\text{ mEq/L}$

A peripheral blood smear demonstrates 3 to 5 schistocytes per high-power field. Which of the following is the most appropriate next step in the management of this patient?

A
Administer nebulized albuterol and ipratropium
B
Administer intravenous vancomycin and cefepime
C
Administer intravenous sodium bicarbonate
D
Administer intravenous levothyroxine
Initiate oral captoprilAnswer

Answer

Initiate oral captopril

This patient is presenting with scleroderma renal crisis (SRC), a severe and potentially life-threatening complication of systemic sclerosis. SRC is characterized by the acute onset of malignant hypertension, oliguric acute kidney injury, and microangiopathic hemolytic anemia (evidenced by schistocytes on peripheral smear and thrombocytopenia). A major known risk factor for precipitating SRC is the recent use of high-dose corticosteroids (e.g., prednisone

>15\text{ mg/day}

), which this patient was prescribed three weeks ago for joint pain. The underlying pathophysiology involves profound activation of the renin-angiotensin-aldosterone system (RAAS) leading to severe vasoconstriction and vascular injury. Therefore, the immediate treatment of choice is a short-acting ACE inhibitor, such as oral captopril. ACE inhibitors are life-saving in this condition and must be initiated promptly, even in the presence of acute kidney injury.

Step-by-Step Solution

Analyze the patient's clinical presentation and recent medication history.

A patient with systemic sclerosis, recently started on high-dose prednisone, presents with malignant hypertension (

225/115\text{ mmHg}

), new-onset acute kidney injury, and microangiopathic hemolytic anemia (evidenced by schistocytes and thrombocytopenia).

Identifying the clinical triad and the medication trigger is essential for accurate diagnosis.

Establish the underlying diagnosis.

The clinical picture is diagnostic of scleroderma renal crisis (SRC), a life-threatening complication of systemic sclerosis that is frequently precipitated by the use of high-dose glucocorticoids.

Recognizing SRC directs immediate, disease-specific intervention rather than supportive care alone.

Determine the most appropriate pharmacotherapy.

The treatment of choice for SRC is the prompt administration of a short-acting ACE inhibitor, such as captopril.

ACE inhibitors reverse the severe renin-angiotensin-aldosterone system activation that drives the crisis, and they must be initiated even in the setting of acute kidney injury.

Key Concept

Scleroderma renal crisis is characterized by acute renal failure, malignant hypertension, and microangiopathic hemolytic anemia. It is often precipitated by high-dose corticosteroid use, and the cornerstone of therapy is immediate ACE inhibitor administration.

Estimated Time:1m 30s

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