Renal function in 153 manic-depressive patients treated with lithium for more than five years

Renal function was examined in 153 manic-depressive patients treated with lithium for more than 5 years, mean 10 years. No significant change was detectable in plasma creatinine. Glomerular filtration rate (GFR) decreased slightly, but significantly, and not until after 17 years of treatment did the regression line reach the lower confidence limit in the reference material. GFR was generally only moderately decreased. Renal concentrating capacity was significantly reduced during the whole investigation period and did not change with time. GFR was independent of the dosage pattern. The diuresis did not differ markedly in patients given one or three daily doses. In a two-dose group predominantly treated with slow-release tablets, the diuresis was somewhat higher in 75% of the patients but much higher for the rest of the group. Since the prophylactic effect of lithium was the same in the one-dose group (mean dosage 21 mmol/day) as in the two-dose and three-dose groups (mean dosage 27-28 mmol/day), our data indicate that generally employed lithium doses may be reduced somewhat without loss of prophylactic efficacy.