Background: Lithium is the most effective therapeutic modality for the prevention of recurrences in bipolar disorder. An important adverse effect of lithium, especially with long-term treatment, is a possibility of a toxic effect on kidney function. Therefore, the aim of the study was to assess kidney function in a group of long-term lithium-treated patients.
Material/Methods: The study comprised 80 patients with bipolar mood disorder (26 male, 54 female), aged 60±11 years. They had been receiving lithium for 5–38 (16±9) years. Random urine sample was examined for albumin and creatinine excretion, and urinary albumin to creatinine ratio (UACR) was calculated. Specific gravity of the urine sample was recorded. Serum concentration of creatinine was measured and estimated glomerular filtration rate (eGFR) was calculated. Serum concentration of albumin was also measured.
Results: Decreased eGFR values <60 ml/min/1.73 m2 were found in 23% of patients, significantly more frequently in men that in women (38% vs. 16%, p=0.04). Elevated UACR values (>30 mg/g) were found in 25% of men and 12% of women, respectively. Serum albumin concentration >52 g/l was detected in 19% of patients (17% of men and 20% of women). Specific gravity of the urine, equal to or below 1.005, was recorded in 21% of men and 14% of women.
Conclusions: The results confirm the opinion that screening for the markers of kidney damage should be performed in long-term lithium-treated patients for identification of persons with impaired kidney function. Male sex seems to be the risk factor for the development of kidney damage during long-term lithium treatment.

Keywords: Lithium - adverse effects, Kidney - physiopathology, Glomerular Filtration Rate, Creatinine - urine, Biological Markers - urine, Albuminuria - physiopathology, Serum Albumin - metabolism, Specific Gravity, Time Factors