A 61-year-old man with decompensated cirrhosis secondary to metabolic dysfunction-associat… — USMLE Step 2 CK

A $61$ -year-old man with decompensated cirrhosis secondary to metabolic dysfunction-associated steatohepatitis (MASH) is evaluated in the progressive care unit for acute kidney injury. He was admitted four days prior for tense ascites, at which time he underwent an uncomplicated $6$ -liter therapeutic paracentesis. Currently, he reports feeling fatigued but denies abdominal pain, fever, or shortness of breath. His daily urine output has declined to $350$ mL over the past $24$ hours. Spironolactone and furosemide were discontinued two days ago when an initial rise in creatinine was noted.

A urine culture collected on admission grew $>100,000$ CFU/mL of *Escherichia coli* pan-susceptible to all tested agents, and he has been receiving targeted oral amoxicillin.

Vital signs are temperature $37.1^\circ$ C ( $98.8^\circ$ F), blood pressure $96/58$ mmHg, and pulse $86$ /min. Physical examination reveals scleral icterus, a protuberant abdomen with a positive fluid wave, and bilateral pitting edema up to the mid-calves.

Laboratory findings:
Hemoglobin: $10.2$ g/dL
Leukocyte count: $6,800/\mu$ L
Serum sodium: $131$ mEq/L
Blood urea nitrogen: $68$ mg/dL
Serum creatinine: $2.8$ mg/dL (baseline at admission: $1.1$ mg/dL)
Urine sodium: $8$ mEq/L
Urinalysis: occasional hyaline casts, no red blood cells, negative for protein

A repeat diagnostic paracentesis performed this morning yields fluid with a total leukocyte count of $120/\mu$ L and $15\%$ neutrophils. An ultrasound of the kidneys shows normal cortical echogenicity without hydronephrosis. Over the preceding $24$ hours, the patient received a continuous infusion of intravenous isotonic crystalloid totaling $2.5$ liters, but his repeat serum creatinine today remains unchanged at $2.8$ mg/dL.

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

Intravenous administration of albuminAnswer
B
Initiation of midodrine and octreotide therapy
C
Escalation of antimicrobial therapy to intravenous piperacillin-tazobactam
D
Consultation for urgent hemodialysis
E
Evaluation for transjugular intrahepatic portosystemic shunt

Answer

The correct answer is the intravenous administration of albumin.

The correct answer is the intravenous administration of albumin. Hepatorenal syndrome (HRS-AKI) is a unique form of functional renal failure in patients with advanced cirrhosis, characterized by severe renal vasoconstriction. However, because these patients have profound splanchnic vasodilation and reduced effective circulating volume, pre-renal azotemia from volume depletion is the most common cause of acute kidney injury. In cirrhosis, crystalloid solutions rapidly shift into the extravascular space (third-spacing) due to portal hypertension and hypoalbuminemia, making them highly ineffective at expanding the effective arterial volume. Therefore, before diagnosing HRS and initiating vasoconstrictor therapy, current AASLD guidelines mandate a volume expansion challenge specifically with intravenous albumin (typically 1 g/kg/day for 2 consecutive days). The lack of response to 2.5 liters of isotonic crystalloids does not fulfill this diagnostic requirement.

Step-by-Step Solution

Identify the etiology pattern of acute kidney injury in this patient.

The patient has pre-renal physiology (indicated by a low urine sodium of 8 mEq/L and occasional hyaline casts) with no response to 2.5 liters of intravenous crystalloids.

Differentiating true volume depletion from hepatorenal syndrome (HRS-AKI) is the critical diagnostic branch point.

Determine if the diagnostic criteria for Hepatorenal Syndrome have been met.

The criteria have not been met. Diagnosis requires the absence of renal improvement after at least 48 hours of diuretic withdrawal and plasma volume expansion specifically with intravenous albumin.

Crystalloids freely diffuse out of the intravascular space in cirrhosis due to profound portal hypertension and hypoalbuminemia, making them inadequate for expanding effective arterial volume.

Select the next best step in management based on guidelines.

The patient must receive an intravenous albumin challenge (1 g/kg/day).

To adequately treat potential uncorrected pre-renal azotemia and complete the diagnostic workup for HRS-AKI.

Key Concept

Diagnosis of Hepatorenal Syndrome (HRS-AKI) requires failure of renal function to improve after a therapeutic volume expansion challenge with intravenous albumin; crystalloid fluids are inadequate for this purpose.

Estimated Time:1m 30s

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