Effects of long-and short-Term lithium treatment on kidney functioning in patients with bipolar mood disorder -

Objective: Lithium carbonate (Li) has been reported to be able to cause some reversible functional changes in the kidney. In this study, we aimed to investigate whether the duration of Li treatment is the primary determinant of the changes in renal functioning due to the Li treatment. For this purpose, we compared renal indices of the patients who were Li-naive, and on short- and long-term Li treatments. Methods: Ten Li-naive (mean age±SD: 34.50±4.85), 10 short-term (mean age±SD: 31.77±7.61) and 10 long-term (mean age±SD: 36.60±10.15) Litreated bipolar patients were included in the study. Serum BUN and creatinine, urine creatinine levels, creatinine clearance, urine osmolality before and after 8-h water deprivation and urine osmolality after desmopressin injection were measured in all patients. Statistical comparisons of the renal values of the groups were carried out with one-way ANOVA. Results: Serum BUN and creatinine levels were within the normal limits and not statistically different among the groups. Creatinine clearance of the long-term Li-treated group was significantly lower than both that of the Li-naive group and that of the short-term Li-treated group. After 8-h water deprivation and also after desmopressin injection, no difference was found among the groups in terms of urine osmolality. However, when each patient was evaluated individually in terms of their renal concentrating ability, partial nephrogenic diabetes insipidus was diagnosed in 4 patients on long-term and in 2 patients on short-term Li-treatment. To our surprise, hypothalamic diabetes insipidus was also diagnosed in other 2 patients on long-term Li-treatment. Conclusion: These results demonstrate that long-term Li treatment may cause impairment in renal concentrating ability some of which may originate from the effects of Li on vasopressin on hypothalamic level, and a decrease in glomerular filtration rate. In the light of these data, we can conclude that the duration of Li treatment is one of the main determinants of Li-induced renal changes in bipolar patients.