Abstract: FR-PO0462
When the Clinical History Does Not Fit: An Unusual Case of Acute Interstitial Nephritis
Session Information
- AKI: Case Reports - TMA, Vasculitis, Immune-Mediated Injury, and Systemic Disease
October 23, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Acute Kidney Injury
- 102 AKI: Clinical, Outcomes, and Trials
Authors
- Sarita Abreu, Marielys, Hospital General de la Plaza de la Salud, Santo Domingo, Dominican Republic
- Marten, Juan C., Hospital General de la Plaza de la Salud, Santo Domingo, Dominican Republic
- Caraballo, Jessibel María, Hospital General de la Plaza de la Salud, Santo Domingo, Dominican Republic
- Rojas, Limber Ivan, Hospital General de la Plaza de la Salud, Santo Domingo, Dominican Republic
Introduction
Acute interstitial nephritis (AIN) is a common cause of intrinsic acute kidney injury (AKI), usually associated with antibiotics, nonsteroidal anti-inflammatory drugs, and proton pump inhibitors. We present a case of fentermina-induced AIN confirmed by renal biopsy.
Case Description
A 42-year-old woman with obesity presented with severe low back pain, dysuria, diarrhea, and progressive anuria over three days. On admission, serum creatinine was 2.5 mg/dL, increasing to 6.8 mg/dL during hospitalization. Initial studies showed leukocytosis, leukocyturia, microscopic hematuria, and bilateral pyelocaliectasis on renal ultrasound, initially suggesting an infectious etiology. Despite intravenous hydration, renal function continued to deteriorate.Laboratory tests showed a decreased BUN/creatinine ratio, suggesting intrinsic acute kidney injury. Pulse therapy with methylprednisolone 1 g for three days was administered. Immunological and viral workup, including ANA, ANCA, anti-dsDNA, and complement levels, was negative. On day five, a directed medical history revealed chronic use of phentermine for weight loss, discontinued one week prior to admission. Renal biopsy confirmed drug-induced acute interstitial nephritis associated with acute tubular necrosis. The patient subsequently developed a polyuric phase with progressive recovery of renal function
Discussion
This case highlights the diagnostic challenge of AKI when the medication history is unclear. Phentermine-induced acute interstitial nephritis is extremely rare, with only scarce reports in the literature, including BMJ Case Reports. Kidney biopsy remains essential for diagnosis. Careful questioning about non-prescribed drugs and supplements is crucial, as early withdrawal of the offending agent is key to recovery.