A Cross Sectional Study To Compare Serum Lithium, Salivary Lithium And Urinary Lithium In Patients On Lithium Carbonate

Abstract

Background and Objectives: ABSTRACT Lithium carbonate is used in the treatment of psychiatric and non psychiatric disorders.Lithium has an established use in treatment of acute mania, prophylaxis of bipolar episodes and augmentation therapy for severe, refractory depression. The difference between toxic and therapeutic dose of lithium carbonate is narrow. Lithium therapy is monitored using series of serum determinations of lithium which requires repeated drawing of blood samples. An alternative method of determining lithium level is to assay salivary gland secretions or urine which has several practical advantages. This study is an attempt to explore the relationship between serum lithium, salivary lithium and urinary lithium, with the possibility of discovering alternate methods for monitoring patients who are on lithium therapy Materials and methods: Blood, saliva and urine samples were collected from 50 patients in the morning (12hrs after the last dose of lithium carbonate) before the patient consumed breakfast and the morning dose of lithium. Samples were collected under aseptic precautionary measures. Estimation of serum, salivary and urine lithium was done using atomic absorption spectrophotometer. Statist ical analysis was done using Pearson’s correlation coefficient and linear regression analysis. Results Mean serum lithium was 0.75±0.25 mEq/L, mean salivary lithium was 1.91±0.80 mEq/L and mean urine lithium was 7.16±4.84 mEq/L. In males mean serum lithium was 0.75±0.26 mEq/L, mean salivary lithium was 1.91±0.80 mEq/L x and mean urine lithium was 7.53±5.26 mEq/L. Correlation between serum lithium and salivary lithium was statistically significant (r=0.695, p <0.001). This correlation was more in females(r=0.770, p <0.001) when compared to males (r=0.665, p <0.001). After doing linear regression analysis, the equation for calculating serum lithium from salivary lithium was: Y=0.332+0.221X (Y=serum lithium concentration, X=salivary lithium concentration). Interpretation and conclusion: This study showed that there is a significant correlation between serum and salivary lithium levels. By using more sophisticated technique, this correlation can be utilized to predict serum lithium levels from salivary lithium level. The relationship found between serum and urine lithium was not statistically significant therefore urine lithium estimation may not be a suitable alternative for monitoring lithium therapy