Renal Histopathological Changes in Patients Treated with Lithium for Bipolar Disorder

BACKGROUND: Lithium remains a cornerstone in the treatment of bipolar disorder, but its long-term use is associated with progressive renal toxicity. Histopathological evaluation of the kidneys offers valuable insight into lithium-induced damage, often before clinical symptoms appear. OBJECTIVES: To evaluate renal histopathological changes in patients treated with lithium for bipolar disorder and to assess the correlation between duration of lithium use and severity of renal injury. METHODS: This was a cross-sectional observational study conducted at Dr. Vaishampayan Memorial Government Medical College, Solapur, from January 2015 to January 2017. Fifty patients with bipolar disorder receiving lithium for at least one year and showing signs of renal dysfunction underwent renal biopsy. Biopsy specimens were analyzed for glomerular, tubular, interstitial, and vascular changes. Clinical data were collected from records and correlated with histopathological findings using statistical tests. RESULTS: The most common histological findings were tubular atrophy (76%), interstitial fibrosis (68%), and chronic interstitial nephritis (44%). Microcystic tubular dilatation, considered a characteristic feature of lithium nephropathy, was observed in 28% of patients. Focal segmental or global glomerulosclerosis was seen in 22% of cases. A significant positive correlation was found between the duration of lithium use and severity of tubulointerstitial changes (p < 0.01). No immune complex deposition was detected. CONCLUSION: Chronic lithium therapy is associated with a spectrum of renal histopathological changes, predominantly tubulointerstitial in nature. The severity of damage increases with treatment duration. Regular renal monitoring and early clinical intervention are essential to prevent irreversible nephropathy in lithium-treated patients