Forty lithium-treated manic-depressive patients underwent two renal
function assessments 6 to 18 months apart to assess the course of renal
function changes associated with lithium therapy. No change in glomerular
filtration rate was noted. Although the average 24-hour urine volume
increased significantly, large increases occurred in few patients. Most
patients had no substantial urine volume change, and a few had decreases.
The changes were correlated with serum lithium levels. The results suggest
that the majority of patients develop little renal concentrating
impairment, while a small proportion of patients become more polyuric with
further lithium treatment.