engleski

Correlation between lithium dose and its serum concentration

Lithium is the third element of the periodic system, which is normally found in living organisms. Since the 1970s, lithium has been used in the treatment of manic states in patients with manic depressive disorders. As lithium therapy is characterized by a narrow therapeutic spectrum associated with significant side effects, the aim of the study was to assess the association between serum lithium concentration and incidence of side effects. Fasting serum concentrations of lithium were determined in 30 patients treated at the Department of Psychiatry Sestre milosrdnice University Hospital, who were receiving 300, 600 or 900 mg lithium per day. Lithium concentration was determined by the colorimetric method based on the sample lithium binding to azo dye (6-dodecyl-6-(2˘hydroxy-5˘-(2˘˘-4˘˘-dinitrophenylazo) benzil-13, 13-dimethyl-1, 4, 6, 11-tetraoxacyclotetradecane) whereby an absorption shift from 400 to 600 nm occurs (Vitros Li slides, Ortho-Clinical Diagnostics, Johnson-Johnson Co. ; Kodak Ektachem analyzer). Therapeutic spectrum ranges from 0.5 to 1.2 mmol/L. Patients were divided into three groups according to daily lithium dose: 300 mg (A), 600 mg (B), and 900 mg (C). Serum level of lithium was 0.64 mmol/L in group A and 1.17 mmol/L in group B, whereas in group C it surprisingly varied from <0.2 to 1.04 mmol/L. Monitoring of serum lithium concentrations revealed considerable dose-dependent differences and showed the lithium serum concentration to correlate with the incidence of side effects. Results of the study pointed to the importance of proper control of the serum lithium concentration in manic depressive patients on lithium therapy.

lithium; therapeutic concentrations; side effects

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