A historical cohort study of kidney damage in long-term lithium patients: continued surveillance needed.

BACKGROUND

Insufficient knowledge on the longitudinal fate of renal function in lithium patients incited this retrospective study of 149 patients.

METHOD: Medical record review of a lithium cohort (N = 149), 8--12 years after an initial renal function study.

RESULTS

Twenty-one patients had died, one from uremia probably not caused by lithium, and 42 had discontinued lithium. Reduced urinary concentrating capacity (Umax) or glomerular filtration rate (GFR) was not more frequent among deceased or off-lithium patients than among the 86 patients who were on lithium at follow-up. In 63 of the latter patients, Umax had been re-examined after the initial study, and GFR in 29 patients. Reduced Umax and GFR had become twice as common, and average Umax and GFR had decreased significantly. The reduction of GFR was associated with lithium treatment duration and age, and reduced Umax with treatment duration only.

CONCLUSIONS

Reduced renal function is not a major cause of treatment discontinuation but becomes increasingly common with treatment duration.Limitations. Missing data rendered the interpretation difficult in some respects. Clinical relevance. The increased proportion of patients with reduced GFR and Umax with time implies an increased risk of potentially lethal dehydration and lithium intoxication. Continued surveillance of urinary output and GFR is therefore necessary.