Lithium-Associated Hypothyroidism in a Specialized Lithium Clinic at a Tertiary Care Hospital in Riyadh, Saudi Arabia: A Retrospective Study.

Hypothyroidism is a common side effect of lithium use and is associated with a slower response to treatment and poorer long-term remission in patients with bipolar disorder. No studies have examined the prevalence of lithium-associated hypothyroidism or its associated factors in Saudi Arabia. We aimed to estimate the prevalence of lithium-associated hypothyroidism among psychiatric patients in a specialized lithium clinic at a tertiary care hospital in Saudi Arabia and to examine the possible risk factors for its development. This retrospective observational study included 117 participants. The prevalence of secondary hypothyroidism was 15%. The median duration between the start of lithium therapy and the first abnormal thyroid test result was 341 days. The multiple logistic regression showed that none of the studied variables, namely, sex, current age, age of lithium initiation, continuity on lithium, lithium level (≤0.5 mmol/L or >0.5 mmol/L), and prescription of as-needed medications, was significantly associated with secondary hypothyroidism. Our study also shed light on the possible clinical significance of baseline TSH levels in developing hypothyroidism secondary to lithium. Further multicenter studies with larger sample sizes are warranted to examine the generalizability of these results.