A longitudinal assessment of renal function during treatment with lithium

Renal function was studied during lithium treatment in 28 patients on two occasions separated by a mean interval of 4.7 years. Glomerular filtration rate, assessed by creatinine clearance and serum creatinine concentrations, showed no impairment. Albumin excretion rate, a marker of glomerular permeability, showed no consistent change. In contrast, a decline in urine concentrating ability (mean 140 mOsm/kg) was found in all patients, exceeding the reduction to be expected from ageing in all but three. These results support the view that treatment with lithium long-term does not damage renal glomerular function, but that progressive impairment of the distal tubular responsiveness to arginine vasopressin is common.