A cross-sectional study of glomerular function in 740 unselected lithium patients.

Creatinine clearance was estimated using a formulaic method from serum creatinine, age and sex in 740 unselected lithium-treated patients in southeastern Scotland. Psychiatric history and details of prescribing and monitoring of lithium treatment were obtained from existing case registers. Lithium treatment duration and glomerular filtration, controlling for the effects of age, were weakly related, but only in males. Cases who had been exposed to higher serum lithium concentrations had lower creatinine clearance than those maintained within therapeutic range. Of cases within the lowest quartile of renal function, proportionally more were supervised in general practice rather than at hospital clinics. Suggestions are made for the clinical practice of monitoring serum lithium concentrations and serum creatinine.