Internal Medicine Acute Kidney Injury Questions and Answers

Question 1

A 75-year-old man with heart failure is admitted with decompensation and treated aggressively with intravenous furosemide. His baseline creatinine was 1.2 mg/dL. On day 3, his creatinine is 2.5 mg/dL and his urine output is low. His blood pressure is 105/65 mmHg. Which set of urine findings is most consistent with pre-renal azotemia from over-diuresis?

Accepted Answer

Urine Sodium < 20 mEq/L, FeNa < 1%, bland sediment

Answer

Pre-renal azotemia is caused by decreased renal perfusion. In response, the healthy tubules avidly reabsorb sodium and water to conserve volume. This leads to concentrated urine with a low urine sodium (<20 mEq/L) and a fractional excretion of sodium (FeNa) less than 1%. The sediment is typically bland or may show hyaline casts. Muddy brown casts are pathognomonic for Acute Tubular Necrosis (ATN). RBC casts suggest glomerulonephritis. WBC casts and eosinophils suggest Acute Interstitial Nephritis (AIN).

Question 2

A 45-year-old male is found down after a reported seizure. He is confused with diffuse muscle tenderness. His creatinine is 2.1 mg/dL, and a urine dipstick is strongly positive for blood but microscopic analysis shows 0-2 RBCs/hpf. His creatine kinase (CK) level is 45,000 U/L. What is the most critical initial step in managing his acute kidney injury?

Accepted Answer

Aggressive intravenous fluid resuscitation with isotonic saline

Answer

The patient has rhabdomyolysis-induced AKI, evidenced by the high CK and myoglobinuria (positive blood on dipstick with no RBCs). The cornerstone of management is early and aggressive intravenous fluid resuscitation with isotonic crystalloids to increase urine flow, flush out myoglobin casts, and prevent further renal tubular injury. While urine alkalinization is sometimes considered, it is secondary to and should not delay aggressive volume repletion. Dialysis is reserved for severe complications like refractory hyperkalemia or fluid overload, and N-acetylcysteine has no role.

Question 3

A 68-year-old male with a baseline creatinine of 1.8 mg/dL and diabetes mellitus is scheduled for a cardiac catheterization requiring intra-arterial contrast. Which of the following interventions has the strongest evidence for preventing contrast-induced acute kidney injury (CI-AKI)?

Accepted Answer

Intravenous isotonic saline infusion before and after the procedure

Answer

The most effective and evidence-based strategy for preventing CI-AKI in high-risk patients is periprocedural volume expansion with intravenous isotonic crystalloids, such as 0.9% saline. This maintains renal perfusion and tubular flow. While sodium bicarbonate has been studied, its superiority over saline is not definitively established. N-acetylcysteine has shown conflicting results and is not consistently recommended. Furosemide is contraindicated as it can cause volume depletion and worsen kidney injury.

Question 4

A 58-year-old male with decompensated alcoholic cirrhosis and ascites is hospitalized. His baseline creatinine of 0.9 mg/dL has risen to 2.5 mg/dL over two days. He is not in shock, has not received nephrotoxic drugs, and a renal ultrasound is normal. Urine sodium is < 10 mEq/L. After a 2-day trial of diuretic cessation and volume expansion with 1 g/kg of albumin, his creatinine does not improve. Which of the following is the most appropriate next step in management?

Accepted Answer

Administration of midodrine, octreotide, and continued albumin

Answer

This patient meets the diagnostic criteria for Hepatorenal Syndrome-Acute Kidney Injury (HRS-AKI). After ruling out other causes and failing to respond to a trial of albumin expansion, the standard of care is medical therapy with splanchnic vasoconstrictors (octreotide) and a systemic vasoconstrictor (midodrine), along with continued albumin. This combination counteracts the splanchnic vasodilation and improves renal perfusion. TIPS and dialysis are second-line or bridging therapies to liver transplantation, which is the definitive treatment.

Question 5

A 62-year-old female with severe acute kidney injury (creatinine 6.8 mg/dL) secondary to sepsis is being managed in the ICU. Which of the following findings is the most urgent indication for initiating renal replacement therapy?

Accepted Answer

Pericardial friction rub on auscultation

Answer

The classic indications for urgent dialysis are remembered by the mnemonic AEIOU: Acidosis (severe), Electrolytes (refractory hyperkalemia), Intoxications, Overload (refractory), and Uremia (symptomatic). A pericardial friction rub is a sign of uremic pericarditis, a life-threatening complication of uremia, and is an absolute indication for immediate dialysis. While refractory hyperkalemia is also an urgent indication, uremic pericarditis represents severe end-organ toxicity requiring the most emergent intervention. An elevated BUN or moderate acidosis alone are not absolute indications.

Internal Medicine Exam Practice Test

Internal Medicine Exam Practice Test

Internal Medicine Acute Kidney Injury Questions and Answers