A Prospective 1-Year Study of Renal Recovery in Pigment Nephropathy: Insights Beyond the Acute Phase

Pigment nephropathy is an underrecognized cause of acute kidney injury. Data from northern India is scarce. The present study aims to assess the clinical characteristics and outcomes of pigment nephropathy in this region.

We analyzed the demographics, etiology, and outcomes of 20 patients with biopsy-proven pigment nephropathy.

The mean age was 27.75 years (range: 13-52), with a male-to-female ratio of 18:2. The average peak serum creatinine was 12.09 mg/dL (range: 0.84-22.3). Rhabdomyolysis was identified in 14 (70%) and hemolysis in 6 patients (30%). The rhabdomyolysis was attributed to hypokalemia, infection, strenuous exercise, physical trauma, inflammatory myositis, neuroleptic malignant syndrome, and heat stroke. The hemolysis was caused by paroxysmal nocturnal hemoglobinuria, thrombotic microangiopathy, transfusion reaction, rifampicin, and physical stress. The majority of patients (85%) required hemodialysis, with a mean of 6 sessions (range: 3-17). The mean duration of hospitalization was 15.3 days (range: 4-30), and the average time to renal recovery was 3.1 weeks (range: 2-6). All 20 patients survived and achieved complete renal recovery. Of the 20 patients, 13 completed at least 1 year of follow-up, 4 were lost to follow-up, and 3 remain under observation. At 1 year, all 13 patients had normal serum creatinine. None progressed to chronic kidney disease.

Of 20 patients (4.1%) with pigment-induced acute kidney injury (AKI), 70% had myoglobin- and 30% hemoglobin-induced nephropathy. Common causes included hypokalemia, infection, strenuous activity, and paroxysmal nocturnal hemoglobinuria. Hemodialysis was required in 85%, with an average hospital stay of 15.3 days. Among 13 patients with a 1-year follow-up, none developed chronic kidney disease. Overall prognosis appears favorable; however, larger studies with extended follow-up are needed to better characterize long-term outcomes in pigment nephropathy.