E-Poster abstract Pattern of serum lithium levels in consecutive samples over a five year period at a tertiary care centre in India

BACKGROUND: In spite of prevalent use of lithium therapy in clinical settings, there is not much published literature on lithium levels in Indian patient samples AIM: The study aimed to describe the pattern and trend of serum lithium level in consecutive serum lithium estimations between January 2015 and December 2019. It did not include 2020-2021 due to frequent COVID-19 related service disruptions in this period. METHODS: This was a retrospective review of lithium laboratory records for consecutive samples received over a five year period at Department of Psychiatry, AIIMS, New Delhi. RESULTS: A total of 4,376 samples were received over five year period (mean age: 34.98±13.06 years; 62% males; out-patient: 87.4%). One-third (36.3%) samples had serum lithium levels <0.60 mEq/L and a small percentage (3.6%) were in toxic range. Further analysis was restricted to out-patient samples within therapeutic range (0.6-1.2 mEq/L) (N=2,278). One-way between-groups ANOVA (Feb-April, May-July, Aug-Oct, Nov-Jan) was significant (F=3.021; df=3; p=0.029), with LSD post-hoc showing a small but statistically significant difference in mean lithium levels of Aug-Oct compared to Nov-Jan (p=0.007) and Feb-April (p=0.015). Further, serum lithium level was positively correlated to age (p=0.019), serum potassium (p=0.002), and inversely correlated to serum sodium (p<0.001). CONCLUSION: Those with older age and lower sodium levels appear to have higher lithium levels, concordant with existing literature. Serum lithium levels showed a slight but significant elevation in Aug-Oct compared to Nov-Jan and Feb-April. This finding can be explored further with respect to weather variables including temperature and humidity for same period.