The authors conducted a study in which 10 patients with recurrent
affective disorders who responded completely to long-term lithium therapy
but who were otherwise unselected were tested for renal tubular
concentrating and acidification ability. Despite frequent symptoms of
thirst, polyuria, and nocturia, all patients were able to concentrate urine
normally and all showed normal renal tubular acidification ability. A
significant correlation was found between erythrocyte lithium concentration
and maximum urinary osmolality.