Two years after a survey of the kidney function in 237 patients given long-term lithium treatment the patients were invited for re-examination. Of 184 patients who came for the reexamination 147 had continued lithium treatment; in 37 patients the treatment had been discontinued. The lithium-treated patients were compared with a group of 68 manic-depressive patients who were about to be given prophylactic lithium treatment but who had not yet started.
Neither the patients who continued nor the patients who had discontinued lithium showed any deterioration of glomerular filtration rate as assessed through determination of the 24-h creatinine clearance and the serum creatinine concentration; mean values in the lithium-treated patients were the same as mean values in patients not yet given lithium. Impairment of renal water reabsorption, revealed by increased 24-h urine volume and decreased urine osmolality after DDAVP, had progressed in the patients who continued lithium treatment, and multiple regression analysis revealed the duration of treatment and the serum lithium level to be significant predictor variables. In the patients who had discontinued lithium the changes in renal water handling had decreased. The urine volume was the same as that found in the patients not yet given lithium; maximum urine osmolality had not become fully normalized.
Side effects such as thirst, nycturia, tremor, diarrhoea, oedema, and weight gain were found with the same frequency at the second as at the first examination in the patients who had continued lithium. In the patients who had discontinued lithium they were infrequent or absent.