Lithium prophylaxis and the kidney.

We reviewed the records of 44 patients under age 55 with bipolar affective disorder, who were without known systemic illness and receiving lithium prophylactically for a minimum of 6 months. We systematically collected all demographic, family history, and clinical side-effect data. In addition, laboratory results of renal function were compiled. Polyuria was the earliest and most frequent side effect of lithium therapy. Patients receiving other psychotropic medication, plus lithium, showed a significant increased prevalence of polyuria particularly after 3 months of exposure to medication, as compared to patients receiving lithium alone. The onset of polyuria was correlated with duration of lithium treatment and patient's age at initiation of therapy. Our data suggest that polypharmacy, duration of exposure to lithium ion and patient age each predict the development of delayed polyuria, a symptom consistent with interstitial nephritis.