Renal function and lithium treatment: initial and follow-up tests in manic-depressive patients.

Assessment of renal function was carried out in an unselected sample of patients with bipolar manic-depressive disorder receiving lithium for an average period of 4.5 years. Overall, glomerular filtration rate (GFR) fell within the established normal range based on sex and age, whereas measures of urinary concentrating ability were generally impaired. There was no relationship between duration of lithium treatment and either GFR or impairment of urinary concentrating ability. Moreover, there was no evidence of a progressive impairment of glomerular or tubular function in patients re-tested after 2 years. The results of this study confirm the safety of lithium administration in the majority of patients and emphasize the importance of careful clinical monitoring to avoid lithium intoxication.