AKI in a Patient with Urinary Tract Infection, Urinary Crystals, and a Bladder Stone

Abstract

A 56-year-old man with a history of diabetes mellitus type 2 for 13 years, depression, and neurogenic bladder who underwent suprapubic catheter placement 2 years ago presented to the hospital with altered mental status and lower abdominal pain for 2 days. His initial vital signs revealed a BP of 90/60 mm Hg, heart rate of 110 beats per minute, respiratory rate of 22 breaths per minute, and temperature of 37.39 . Physical exam demonstrated suprapubic tenderness. Laboratory studies revealed the following: white blood cells of 14,690 per ml (3000-11,200 per ml), hemoglobin of 11.0 g/dl (12.5-15.9 g/dl), serum creatinine of 3.71 mg/dl (baseline creatinine 1.6 mg/dl), BUN of 104 mg/dl (6-23 mg/dl), serum bicarbonate of 10 mmol/L (22-29 mmol/L), serum anion gap of 25 mmol/L (7-16 mmol/L), whole blood lactate of 5 mmol/L (0.5-1.7 mmol/L), and serum osmolality of 335 mOsm/ kg (275-295 mOsm/kg). Urinalysis revealed a pH of 9.0 with hematuria and pyuria. Examination of the urine sediment by light microscopy demonstrated coffin lid-shaped crystals consistent with triple phosphate crystals (Figure 1A). Under polarized light, the crystals were positively birefringent; crystals were blue when parallel to the light, and yellow when perpendicular to the light (Figure 1B). Computed tomography scan of the abdomen without contrast showed a thickened bladder wall with a large, calcified bladder stone (Figure 2), with no evidence of calculi in the kidneys or ureters. The patient was started on intravenous fluids and antibiotics covering urease-producing bacteria, and a 4.5-cm, yellow-tan, calcified stone was removed emergently by cystoscopy. Urine culture later grew Klebsiella oxytoca and calculus analysis demonstrated a magnesium ammonium phosphate component. On day 3 of hospitalization, the patient clinically improved, with serum creatinine returning to his baseline, and he was discharged on a 14-day course of cefdinir.