Lithium: long‐term effects on the kidney I. Renal function in retrospect

— 46 patients treated with lithium for an average of 8 years participated in a functional-morphological follow-up study based on a 12-day hospitalization and involving a kidney biopsy. The functional part of the study showed that tubular function was markedly influenced, leading to increased urine volume (average 3 1/24 h) and a decreased renal concentration capacity in 85% of the patients. Glomerular function was generally not influenced, and only 10% of the patients had glomerular filtration rates below their age-corrected normal ranges. Both urine volume and glomerular filtration rates showed significant correlations with dosage schedule. Urine volume was lower and glomerular filtration rate higher on a one-dose schedule than when lithium was given in divided doses during the day. It is concluded that discontinuity in lithium treatment minimizes lithium effects on kidney function.