Renal function on and off lithium in patients treated with lithium for 15 years or more. A controlled, prospective lithium-withdrawal study.

BACKGROUND

Controversy remains over the magnitude and reversibility of reduced renal function in long-term lithium patients.

METHODS

Thirteen patients with 18 years (range 15-24) on lithium discontinued the treatment, and were re-examined twice after 5 and 9 weeks (4-16) off lithium. They were compared to a non-lithium psychiatric control group, matched for age and sex.

RESULTS

Glomerular filtration rate (GFR) tended to improve from 69 (39-96) to 74 (39-94) ml/min/1.73 m2 BSA, P = 0.057, which was not significantly different from 78 (61-106 ml/min per 1.73 m2 BSA in the controls. Reduced GFR was found in only two of the lithium patients off lithium, and in none of the controls. Maximal urinary concentrating capacity did not improve at all. It was 637 (130-875) mOsm/kg H2O in the lithium patients, which was lower than 856 (705-1.035) mOsm/kg H2O (P < 0.01) in the controls. Two of the lithium patients had isosthenuria.

CONCLUSIONS

Lithium patients often have an irreversible, clinically important reduction of Umax, sometimes progressing to nephrogenic diabetes insipidus, while GFR is well preserved in most patients.