A 53-year-old woman is brought to the emergency department by her husband due to a severe … — USMLE Step 2 CK

A 53-year-old woman is brought to the emergency department by her husband due to a severe headache, blurred vision, and progressive confusion over the past 24 hours. Her past medical history is significant for diffuse cutaneous systemic sclerosis diagnosed three years ago. Two weeks ago, she was started on oral prednisone for worsening joint pain and skin tightness. Her temperature is 37.1°C (98.8°F), blood pressure is 225/115 mmHg, and pulse is 102/min. Physical examination shows thickened, tight skin over her face, forearms, and chest. Neurological examination reveals a confused patient but is negative for focal motor or sensory deficits. Fundoscopy demonstrates bilateral flame-shaped hemorrhages and papilledema. Laboratory studies show:

Test	Result
Hemoglobin	9.1 g/dL
Platelets	85,000/mm³
Leukocytes	8,400/mm³
Creatinine	3.2 mg/dL

A peripheral blood smear demonstrates 3-5 schistocytes per high-power field. Her baseline creatinine one month ago was 0.8 mg/dL. Which of the following is the most appropriate next step in the pharmacologic management of this patient's condition?

A
Intravenous labetalol
B
Intravenous ceftriaxone and vancomycin
Oral captoprilAnswer
D
Plasma exchange
E
Intravenous methylprednisolone

Answer

Oral captopril

The correct answer is oral captopril. This patient is presenting with Scleroderma Renal Crisis (SRC), a severe and potentially fatal complication that occurs in about 10-15% of patients with diffuse cutaneous systemic sclerosis. SRC is characterized by the sudden onset of marked hypertension (often malignant, presenting with end-organ damage such as encephalopathy and papilledema) and rapidly progressive oliguric acute kidney injury. Approximately half of patients also develop microangiopathic hemolytic anemia (MAHA) and thrombocytopenia, as seen in this patient with schistocytes on her blood smear. A major known trigger for SRC is the recent use of moderate-to-high dose corticosteroids (e.g., prednisone), which this patient recently started taking. The pathogenesis of SRC involves acute intimal proliferation and narrowing of the renal arteries, leading to decreased renal perfusion, massive renin release, and severe activation of the renin-angiotensin-aldosterone system (RAAS). Therefore, the specific and life-saving treatment is rapid RAAS blockade with a short-acting ACE inhibitor, such as oral captopril. Captopril should be initiated immediately and titrated to carefully lower the blood pressure. Notably, ACE inhibitors are the treatment of choice for SRC even in the setting of acute kidney injury, a situation where they are typically contraindicated in other disease states.

Step-by-Step Solution

Analyze the patient's clinical presentation and medical history.

The patient has diffuse cutaneous systemic sclerosis and presents with new-onset malignant hypertension, encephalopathy, acute kidney injury, and microangiopathic hemolytic anemia.

Identifying the classic triad of malignant hypertension, rapidly progressive acute renal failure, and systemic sclerosis establishes the primary clinical syndrome.

Synthesize the laboratory findings with the clinical picture.

The presence of schistocytes, thrombocytopenia, and elevated creatinine confirms Scleroderma Renal Crisis (SRC), which was likely precipitated by her recent initiation of corticosteroid therapy.

Differentiating SRC from primary thrombotic microangiopathies (like thrombotic thrombocytopenic purpura) is critical for selecting the correct physiological target for treatment.

Determine the most appropriate pharmacologic intervention based on pathophysiology.

Immediate administration of a short-acting ACE inhibitor (captopril) is required.

SRC is driven by massive, unabated renin-angiotensin-aldosterone system (RAAS) activation; ACE inhibitors specifically reverse this intense vasospasm and are the only agents proven to restore renal perfusion and improve outcomes.

Key Concept

Scleroderma renal crisis (SRC) is a life-threatening complication of systemic sclerosis characterized by malignant hypertension, acute kidney injury, and often microangiopathic hemolytic anemia. It is treated primarily with ACE inhibitors (e.g., captopril) despite the presence of renal failure.

Estimated Time:1m 30s

Question

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Topics

More questions from this topic