A 45-year-old woman is brought to the emergency department by her husband due to a severe,… — USMLE Step 2 CK

A $45$ -year-old woman is brought to the emergency department by her husband due to a severe, throbbing headache, blurred vision, and worsening shortness of breath over the past $48$ hours. She was diagnosed with diffuse cutaneous systemic sclerosis $3$ years ago. Her home medications include mycophenolate mofetil. She recently visited an urgent care clinic for dysuria, and a urine culture sent at that time grew $>100,000$ CFU/mL of *Escherichia coli* susceptible to amoxicillin, nitrofurantoin, and ceftriaxone. She has not yet started antibiotic therapy.

Today, her temperature is $37.1^\circ C$ ( $98.8^\circ F$ ), blood pressure is $225/125$ mmHg, pulse is $110$ /min, and respirations are $26$ /min. Oxygen saturation is $93\%$ on room air. Physical examination reveals taut, thickened skin over the face, chest, and upper extremities. Funduscopic examination demonstrates bilateral papilledema and flame-shaped hemorrhages. Lung auscultation reveals fine bibasilar crackles.

Laboratory results are as follows:

Test	Result	Reference Range
Hemoglobin	$8.9$ g/dL	$12.0-16.0$ g/dL
Platelets	$85,000$ /mm³	$150,000-400,000$ /mm³
Serum creatinine	$3.4$ mg/dL (baseline $0.8$ )	$0.6-1.1$ mg/dL
Thyroid-stimulating hormone (TSH)	$2.2$ $\mu$ U/mL	$0.5-5.0$ $\mu$ U/mL
Free T4	$0.7$ ng/dL	$0.9-1.7$ ng/dL

Arterial blood gas on room air:
pH: $7.32$
pCO₂: $30$ mmHg
pO₂: $72$ mmHg
HCO₃⁻: $15$ mEq/L

Peripheral blood smear shows numerous schistocytes.

Which of the following is the most appropriate initial step in the management of this patient's condition?

Initiate therapy with an angiotensin-converting enzyme inhibitorCevap
B
Administer intravenous piperacillin-tazobactam
C
Administer intravenous sodium bicarbonate
D
Administer nebulized albuterol and intravenous furosemide
E
Administer intravenous levothyroxine

Cevap

Initiate therapy with an angiotensin-converting enzyme inhibitor

The correct intervention is to initiate an angiotensin-converting enzyme (ACE) inhibitor. This patient is experiencing scleroderma renal crisis (SRC), a medical emergency classically seen in diffuse cutaneous systemic sclerosis. It is characterized by the sudden onset of malignant hypertension, acute kidney injury, and frequently microangiopathic hemolytic anemia (indicated by schistocytes and thrombocytopenia). The pathophysiology involves severe proliferation of the renal arcuate and interlobular arteries, leading to renal ischemia and massive activation of the renin-angiotensin-aldosterone system (RAAS). ACE inhibitors (such as short-acting oral captopril) are uniquely life-saving in SRC. Crucially, even though ACE inhibitors can typically worsen acute kidney injury, SRC is the major exception where they must be aggressively up-titrated to control blood pressure and reverse the primary disease process.

Adım Adım Çözüm

Identify the primary clinical syndrome from the patient's history and vital signs.

A patient with diffuse cutaneous systemic sclerosis presents with malignant hypertension (225/125 mmHg), encephalopathy (headache, blurred vision, papilledema), and acute kidney injury (creatinine 3.4 mg/dL).

Recognizing the triad of systemic sclerosis, severe hypertension, and acute renal failure points directly to scleroderma renal crisis (SRC).

Evaluate the laboratory findings to confirm the diagnosis and rule out complications.

Labs show microangiopathic hemolytic anemia (schistocytes, thrombocytopenia, low hemoglobin) which frequently accompanies SRC due to endothelial injury. Acid-base status shows a fully compensated metabolic acidosis. Thyroid labs reflect euthyroid sick syndrome.

Confirming MAHA supports the severity of the vascular injury in SRC. The other laboratory abnormalities are secondary to the acute illness and AKI.

Determine the most critical pharmacologic intervention for this specific rheumatologic emergency.

Angiotensin-converting enzyme (ACE) inhibitors are the only therapy proven to reverse the profound renin-angiotensin-aldosterone system activation in SRC.

Unlike most other causes of AKI where ACE inhibitors are discontinued, SRC uniquely requires the prompt initiation and rapid titration of short-acting ACE inhibitors (like captopril) to prevent permanent renal failure and death.

Anahtar Kavram

Scleroderma renal crisis (SRC) presents with malignant hypertension, acute kidney injury, and microangiopathic hemolytic anemia in a patient with systemic sclerosis. The cornerstone of management is the immediate initiation of an ACE inhibitor.

Soru

Cevap

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