Free nephrology board questions: AKI

A 22-year-old man is taken to the emergency department by his friend after accidental ingestion of an unknown fluid earlier that day. He complains of abdominal pain but has not experienced any nausea or vomiting. He has no past medical history and takes no medications. On examination, BP is 110/77 mm Hg, heart rate is 112/min, respiratory rate is 19/min, and oxygen saturation is 98% while breathing room air. He appears distressed and is alert to person and place but is unsure of the date. Physical examination reveals mild tenderness to palpation of the abdomen but is otherwise normal. Laboratory data: sodium 142 mEq/L (reference 136–145); potassium 3.8 mEq/L (3.5–5.0); chloride 106 mEq/L (98–106); total CO₂ 14 mEq/L (23–28); BUN 9 mg/dL (8–20); creatinine 0.7 mg/dL (0.7–1.3); glucose 81 mg/dL (70–99, fasting); osmolality 322 mOsm/kg H₂O (275–295). Shortly after arrival, the patient provides a urine sample, which shows blue-green fluorescence under a Wood's lamp. Which ONE of the following is the most appropriate next step in management?

A previously healthy 32-year-old woman who recently moved from Mexico has several months of dysuria, urinary frequency, and flank pain with persistent pyuria; multiple urine cultures have been negative. She has no cough, dyspnea, fever, weight loss, or sick contacts. Urinalysis shows trace protein, pH 4.5, 2+ leukocyte esterase, >50 WBC/hpf, and 10–15 RBC/hpf. CT of the abdomen and pelvis shows a left ureteral stricture with segmental dilations. What is the most appropriate next step?

A 73-year-old man is admitted to the hospital after routine outpatient laboratory testing revealed AKI with a serum creatinine level of 3.8 mg/dL (reference, 0.7–1.3; baseline 1.0). He reports generalized fatigue, urinary hesitancy, and nocturia. He continues to produce urine but reports a decreased volume. On initial examination, BP is 148/88 mm Hg and moderate peripheral edema is present. Initial evaluation included a renal ultrasound that demonstrated bilateral moderate hydronephrosis, an enlarged prostate, and a distended bladder. Initial UA was bland. An indwelling urinary catheter was inserted, which immediately drained 1.2 L of straw-colored urine. Normal saline IV was initiated at 250 mL/h. After 48 hours, his daily urine output has remained >6 L/d, and he is eating and drinking normally. Examination reveals BP 144/82 mm Hg with persistent peripheral edema. Laboratory data (admission, current; reference): sodium 144, 148 mEq/L (136–145); potassium 5.1, 3.7 mEq/L (3.5–5.0); chloride 118, 120 mEq/L (98–106); total CO₂ 18, 19 mEq/L (23–28); BUN 95, 38 mg/dL (8–20); creatinine 3.8, 1.3 mg/dL (0.7–1.3). Which ONE of the following is the next BEST step in management?

A 57-year-old woman with urothelial cancer is evaluated for a subacute rise in her serum creatinine. Six months ago, her creatinine was 1.1 mg/dL, and it has steadily risen to 1.8 mg/dL today. The patient does not have orthostatic or new urinary symptoms. Her urothelial cancer was diagnosed 2.5 years ago, and she was treated with cisplatin and gemcitabine before undergoing radical cystectomy with ileal conduit. Eleven months ago, she was prescribed nivolumab and ipilimumab (immune checkpoint inhibitors) for progressive disease. Her other medications include omeprazole, ondansetron, and folic acid. She does not use NSAIDs or other over-the-counter or herbal medications. On examination, BP is 123/67 mm Hg, and heart rate is 76/min without postural changes. She is afebrile. She has a well-healed and pink ileal stoma in the right lower quadrant of her abdomen. The remainder of her examination is unremarkable. Laboratory data: WBC count 13,500/μL (reference 4000–11,000); hemoglobin 10.2 g/dL (12–16); platelets 302,000/μL (150,000–450,000); serum sodium 138 mEq/L (136–145); potassium 3.7 mEq/L (3.5–5.0); chloride 101 mEq/L (98–106); total CO₂ 24 mEq/L (23–28); BUN 23 mg/dL (8–20); creatinine 1.8 mg/dL (0.5–1.1). Urine: sodium 72 mEq/L (varies); creatinine 45 mg/dL (varies); protein trace (negative); blood trace (negative); ketones negative (negative); leukocyte esterase 3+ (negative); nitrite negative (negative). Urine microscopy shows 0–2 RBCs/HPF, 16–30 WBCs/HPF, and few bacteria. CT scan of the abdomen and pelvis with contrast shows mild bilateral hydroureter to the level of the urinary diversion, unchanged from 1 year ago. Which of the following is the MOST likely cause of decreased kidney function?

A 25-year-old previously healthy female veterinary student presents for worsening malaise, fever, myalgias, headache, and skin discoloration over the last 2 weeks. Medications include as-needed ibuprofen, which she has used sparingly, and a multivitamin. Social history is significant for two alcoholic drinks weekly; she does not use tobacco, inhaled nicotine, or recreational drugs. On examination, BP is 98/46 mm Hg, heart rate is 110/min, and temperature is 39°C. Eye examination is significant for scleral icterus and subconjunctival hemorrhages without purulent exudate. Abdominal examination reveals splenomegaly. Musculoskeletal examination reveals tenderness to palpation of the lower back and both calves. She is jaundiced, but there is no rash. Laboratory data: WBC count 16,000/μL (reference 4000–11,000); hemoglobin 12 g/dL (12–16); platelets 45,000/μL (150,000–450,000); sodium 138 mEq/L (136–145); potassium 2.9 mEq/L (3.5–5.0); total CO₂ 18 mEq/L (23–28); BUN 55 mg/dL (8–20); creatinine 4.0 mg/dL (0.5–1.1); total bilirubin 14 mg/dL (0.3–1.0); direct bilirubin 12 mg/dL (0.1–0.3); aspartate aminotransferase 300 U/L (10–40); alanine aminotransferase 150 U/L (10–40). Peripheral blood smear shows rare schistocytes. Urinalysis shows dark yellow urine with 1+ blood, 8–10 isomorphic RBCs/HPF, and 1–2 granular casts/LPF. Which of the following is the MOST LIKELY diagnosis?

A 76-year-old man presents to the emergency department with fever, chills, and shortness of breath. Past medical history includes CKD stage G3a/A2 attributed to poorly controlled type 2 diabetes and hypertension. BP is 82/54 mm Hg, heart rate is 112/min, respiratory rate is 22/min, and oxygen saturation is 84% breathing room air. On examination, he is somnolent with labored breathing. Heart examination reveals tachycardia and lung examination reveals coarse breath sounds, decreased in the right base. There is no edema. Laboratory data on admission is significant for creatinine 1.3 mg/dL (baseline, 0.9; reference range, 0.7–1.3). Chest x-ray shows a dense, right lower lobe consolidation. EKG is unremarkable. The patient is intubated, and broad-spectrum antibiotics and IV fluids are administered. After 3 hours, BP remains 80/52 mm Hg. Which of the following agents is the next BEST STEP in therapy?

A 68-year-old man in the ICU has dyspnea and malaise that began 4 days ago with diarrhea and vomiting. He has heart failure with preserved ejection fraction, CKD G3b, hypertension, and type 2 diabetes, and adheres to torsemide, carvedilol, lisinopril, amlodipine, and atorvastatin. BP is 98/62 mm Hg, heart rate 106/min, respiratory rate 22/min, SpO₂ 92% on 3 L/min oxygen. He has moist mucous membranes, fine bibasilar crackles, and a regular tachycardia, without jugular venous distention, hepatojugular reflux, or edema; the abdomen is benign. Which test would best indicate whether his hemodynamics will respond to IV fluid?

A 52-year-old man is evaluated for AKI. He has taken omeprazole 20 mg twice daily for the last 3 weeks for indigestion. He is otherwise asymptomatic and has not observed any changes in the volume or character of his urine. BP is 138/82 mm Hg and heart rate is 86/min. Physical examination, including heart, lungs, and abdomen, is unremarkable. No edema or rash is observed. Laboratory data reveal serum creatinine 2.9 mg/dL compared with 0.9 mg/dL from 2 months ago (reference range, 0.7–1.3). Urinalysis is positive for leukocyte esterase but negative for nitrites. Urine microscopy reveals 20 WBC/HPF, and eosinophils account for >6% of the total urinary WBCs, which is considered a positive result at the reference laboratory. A urine culture shows no growth after 72 hours. Despite withdrawal of omeprazole, 5 days later, the creatinine remains 3.0 mg/dL. Acute interstitial nephritis (AIN) is suspected, and a kidney biopsy is recommended. The patient asks if a biopsy is necessary given the presence of urinary eosinophils. To address this question, the physician identifies a study of patients with pyuria and AKI, sufficiently similar to this patient, who had both a urine eosinophil test and a kidney biopsy performed within the same week. A table of results is constructed for the 467 patients with pyuria: urine eosinophils >5%, 18 with biopsy showing AIN and 42 with another biopsy result (total 60); urine eosinophils ≤5%, 55 with AIN and 352 with another result (total 407); totals, 73 with AIN and 394 with another result (467 overall). Based on this study, what is the probability that a kidney biopsy performed in this patient will demonstrate AIN?

A 76-year-old man with stage 3 non-small cell lung cancer is evaluated for increased serum creatinine after initiating cisplatin therapy. He denies shortness of breath, edema, or hematuria. On exam, BP is 110/64 mm Hg and heart rate is 72/min without orthostatic changes. There is trace pretibial edema bilaterally. Laboratory data: WBC count 3200/µL (reference 4000–11,000); hemoglobin 9.6 g/dL (14–18); platelet count 162,000/µL (150,000–450,000); serum sodium 137 mEq/L (136–145); potassium 3.9 mEq/L (3.5–5.0); creatinine 1.7 mg/dL (baseline, 0.7) (0.7–1.3); magnesium 1.3 mEq/L (1.6–2.6); urine protein-to-creatinine ratio 0.6 mg/mg (baseline, 0.2) (<0.2). Urinalysis with microscopy is unremarkable, and urine output is 1200 mL/day. Which ONE of the following is the MOST appropriate intervention to limit cisplatin-associated AKI?

A 25-year-old man admitted to the ICU 5 days ago with fever has a right internal jugular central venous catheter for vasopressors. BP is 80/42 mm Hg, temperature 38.6°C, and BMI 24 kg/m². He has bilateral coarse crackles and generalized edema. Urine output was 30 mL over 24 hours. Chest radiograph shows bilateral pulmonary opacities. Potassium is 6.6 mEq/L, total CO₂ 10 mEq/L, BUN 93 mg/dL, creatinine 5.4 mg/dL, and phosphorus 7.1 mg/dL. Hemodialysis is planned. Bedside ultrasound of the right internal jugular vein shows a catheter-associated thrombus. What is the best approach to obtain dialysis access?

A 50-year-old man with CKD G3b/A1, hypertension, and glucose-6-phosphate dehydrogenase (G6PD) deficiency is admitted to the hospital for a new diagnosis of acute myeloid leukemia. He is scheduled for induction chemotherapy with cytarabine and daunorubicin. Admission laboratory data: WBC count 50,000/µL (reference 4000–11,000); potassium 4.5 mEq/L (3.5–5.0); total CO₂ 24 mEq/L (23–28); creatinine 1.9 mg/dL (0.7–1.3); calcium 8.8 mg/dL (8.6–10.2); phosphorus 3.5 mg/dL (3.0–4.5). He is at intermediate risk for tumor lysis syndrome. In addition to volume expansion, which ONE of the following is the MOST appropriate treatment for preventing tumor lysis syndrome?