Background: Little is known about the rate of thyroid disorders prior to lithium treatment, and which patients have a higher risk for developing such disorders during such treatment.
Method: Assessment of the thyroid histories and laboratory results of 209 lithium-treated patients with affective disorders from one catchment area.
Results: Six female patients had thyrotoxicosis before starting lithium, a rate of 4.9%. Twenty patients developed hypothyroidism during the treatment: 3.4% of all males and 14.9% of all females. Female patients over the age of 50 were more likely to develop early lithium-induced hypothyroidism.
Conclusions: (1) Female patients with affective disorders might have an increased rate of thyrotoxicosis. (2) Lithium-induced hypothyroidism might develop earlier in female patients over the age of 50.
Limitations: Retrospective design of the study.
Clinical relevance: (1) The thyroid status of patients with affective disorders might be more relevant than is appreciated. (2) Guidelines for thyroid tests in lithium-treated patients should reflect the different risks conferred by age and gender.