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Difficulty: MediumRheumatology and Immunology

A 4848-year-old woman comes to the emergency department due to a severe, throbbing headache, blurred vision, and worsening shortness of breath for the past 22 days. She has a 33-year history of diffuse cutaneous systemic sclerosis. Her current medications include mycophenolate mofetil and omeprazole. Her blood pressure is 220/120220/120 mm Hg, pulse is 9898/min, and respirations are 2222/min. Physical examination shows thickened, tight skin over the face, trunk, and upper extremities. Cardiopulmonary examination reveals bilateral basilar lung crackles. Laboratory studies show:

Hemoglobin: 9.29.2 g/dL
Platelets: 95,00095,000/mm 3^3
Creatinine: 2.82.8 mg/dL (baseline 0.90.9 mg/dL)

Peripheral blood smear demonstrates multiple schistocytes. Which of the following is the most appropriate initial treatment for this patient's acute kidney injury and hypertension?

  1. Oral captoprilAnswer
  2. B
    Intravenous esmolol
  3. C
    Intravenous methylprednisolone
  4. D
    Therapeutic plasma exchange
  5. E
    Intravenous nitroprusside

Answer

Oral captopril
The correct answer is oral captopril. This patient with diffuse cutaneous systemic sclerosis is experiencing a scleroderma renal crisis (SRC). SRC is characterized by the sudden onset of marked hypertension, acute kidney injury, and often microangiopathic hemolytic anemia (schistocytes on peripheral smear) with mild thrombocytopenia. The fundamental pathophysiology involves severe narrowing of the renal arterioles, which leads to decreased renal perfusion and massive activation of the renin-angiotensin-aldosterone system (RAAS). ACE inhibitors, specifically short-acting agents like captopril, are the mainstay of therapy because they directly reverse this RAAS hyperactivation. They must be initiated immediately and titrated rapidly, even in the setting of an elevated serum creatinine.

Step-by-Step Solution

1
Identify the acute clinical syndrome based on the patient's presentation.
The patient has malignant hypertension, acute kidney injury, and microangiopathic hemolytic anemia in the setting of diffuse cutaneous systemic sclerosis, diagnostic of Scleroderma Renal Crisis (SRC).
Recognizing the constellation of symptoms in a patient with a specific rheumatologic disease establishes the underlying etiology of the hypertensive emergency.
2
Determine the pathophysiological mechanism driving the crisis.
SRC is caused by rapid narrowing of renal arterioles leading to decreased renal perfusion and massive activation of the renin-angiotensin-aldosterone system (RAAS).
Understanding the mechanism is critical for selecting targeted pharmacotherapy rather than generic blood pressure management.
3
Select the most appropriate targeted intervention.
A short-acting ACE inhibitor (captopril) is chosen to immediately and specifically block the RAAS hyperactivation.
ACE inhibitors are life-saving in SRC and must be initiated even in the presence of an elevated serum creatinine.

Key Concept

Scleroderma renal crisis presents with malignant hypertension, acute kidney injury, and microangiopathic hemolytic anemia. It requires immediate treatment with ACE inhibitors to reverse massive RAAS activation.
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Topics

Rheumatology and Immunology

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