BACKGROUND: This review addresses the definition, prevalence, etiology, and clinical significance of lithium-associated subclinical hypothyroidism and offers guidelines for evaluation and treatment of this condition. DATA SOURCES: MEDLINE was used to search all articles written in English from 1964-present that included the words lithium and thyroid; lithium and subclinical hypothyroidism; mood and thyroid function; and bipolar illness and thyroid function. STUDY FINDINGS: Lithium interferes with thyroid metabolism and increases the incidence of overt and subclinical hypothyroidism. Subclinical hypothyroidism may be associated with the presence of somatic and neuropsychiatric symptoms and interfere with treatment responsiveness. CONCLUSION: A careful assessment of thyroid function is recommended prior to initiating lithium treatment and during maintenance treatment. Recommendations regarding the threshold for initiation of thyroxine supplementation in patients with lithium-associated subclinical hypothyroidism are discussed in relationship to the degree of detrimental effects potentially associated with thyroid dysfunction.
BACKGROUND: This review addresses the definition, prevalence, etiology, and clinical significance of lithium-associated subclinical hypothyroidism and offers guidelines for evaluation and treatment of this condition. DATA SOURCES: MEDLINE was used to search all articles written in English from 1964-present that included the words lithium and thyroid; lithium and subclinical hypothyroidism; mood and thyroid function; and bipolar illness and thyroid function. STUDY FINDINGS:Lithium interferes with thyroid metabolism and increases the incidence of overt and subclinical hypothyroidism. Subclinical hypothyroidism may be associated with the presence of somatic and neuropsychiatric symptoms and interfere with treatment responsiveness. CONCLUSION: A careful assessment of thyroid function is recommended prior to initiating lithium treatment and during maintenance treatment. Recommendations regarding the threshold for initiation of thyroxine supplementation in patients with lithium-associated subclinical hypothyroidism are discussed in relationship to the degree of detrimental effects potentially associated with thyroid dysfunction.