Early identification of renal problems in patients receiving chronic lithium treatment.

Serum beta 2-microglobulin and creatinine values were compared with creatinine clearance in 20 lithium-treated patients. beta 2-microglobulin, but not creatinine, correlated significantly with creatinine clearance, indicating that beta 2-microglobulin is a more sensitive test than serum creatinine for monitoring glomerular filtration rate in chronic lithium therapy.