Lithium treatment reduces the renal kallikrein excretion rate. Kidney Int

Lithium treatment reduces the renal kalHkrein excretion rate. Lithium salts are widely used agents for the prophylactic treatment of affective disorders. Lithium salts may be associated with distal nephron dysfunc-tion. Kallikrein is a protease which is generated by the distal nephron. We used an amidolytic assay of chromatographically purified enzyme to determine the urinary excretion rate of active kallikrein in relation to lithium treatment. All plasma lithium concentrations were within the therapeutic range (0.4 to 0.9 mmol/liter). In 15 patients the urinary excretion rate of active kallikrein was 267.4 ± 65.6 mU/24 hrs before lithium treatment, and fell to 117.8 ± 39.6 mU/24 hrs (P < 0.05) on day 14 of lithium treatment. This reduction was associated with a decrease of immunoreactive kallikrein in the same urines by 66%. In another 15 patients who had undergone lithium therapy for an average period of 5.6 years, the urinary excretion rate of active kallikrein was 86.1 ± 14.5 mU/24 hrs, while 21 age-matched healthy controls had an excretion rat