Acute tubulointerstitial nephritis induced by intravesical bacillus Calmette-Guerin: a rare case of acute kidney injury.

Background: Intravesical bacillus Calmette-Guerin (IVBCG) is considered the most optimal follow-up therapy for high-risk urothelial cancers. Although side effects such as cystitis, hematuria, and low-grade fever are common, they are generally mild. Severe reactions involving the kidneys are extremely rare. Here, we present the case of a 64-year-old male who developed acute renal failure due to acute tubulointerstitial nephritis (ATIN) following the first IVBCG administration. We have also conducted a literature review concerning IVBCG-induced nephritis.

Case report: A 64-year-old male presented to the Nephrology Department with acute kidney injury indicators and hematuria. The patient was suffering from high-grade papillary urothelial carcinoma. Transurethral resection of the bladder tumor was performed twice and followed by one IVBCG administration - two days before the symptoms occurred. The latest follow-up cystoscopy excluded the recurrence of the cancer. Laboratory tests displayed hyperkalemia, decreased glomerular filtration rate (GFR = 4 ml/min/1.73 m2), elevated C-reactive protein, and acute metabolic acidosis. Urinalysis showed proteinuria (900 mg/24 h), leukocyturia, and erythrocyturia (20,402.7 per microliter). Renal ultrasound demonstrated slight bilateral renal enlargement. The patient was identified with acute tubulointerstitial nephritis (ATIN). The treatment involved intravenous methylprednisolone (250 mg three times every two days and then 125 mg four times every two days), fol-lowed by oral methylprednisolone (24 mg and 12 mg daily alternately for a week). Piperacillin and tazobactam, probiotics, and proton pump inhibitors were also administered. Hemodialysis was conducted three times. Two weeks after the admission, a significant improvement was observed: creatinine decreased to 2.04 mg/dl, and GFR increased to 33 ml/min/1.73 m2. The patient was discharged with a recommendation to reduce the dose of glucocorticosteroids and continued in the outpatient clinic.

Conclusions: IVBCG may lead to acute kidney injury due to ATIN. Symptoms may occur as early as after the first IVBCG, contrary to previous reports. Patients should be regularly assessed for potential complications, including creatine level measurement, after each IVBCG treatment.