Effect of lithium on hypothalamic-pituitary-thyroid function in patients with affective disorders

Area of Science:

• Endocrinology
• Pharmacology
• Neuroscience

Background:

• Lithium carbonate is a common mood stabilizer.
• Its long-term effects on endocrine function require thorough investigation.
• The hypothalamic-pituitary-thyroid (H.P.T.) axis is sensitive to various pharmacological agents.

Purpose of the Study:

• To evaluate the impact of lithium carbonate on H.P.T. axis function.
• To assess thyroid function in patients on maintenance lithium therapy.
• To monitor changes in H.P.T. function from the initiation of lithium treatment.

Main Methods:

• Assessed H.P.T. function in 17 patients on maintenance lithium doses (mean 21 months).
• Conducted serial studies on four patients from lithium treatment start (max 6 months).
• Measured thyrotrophin (TSH) response to thyrotrophin-releasing hormone (TRH) and basal TSH levels.

Main Results:

• An exaggerated TSH response to TRH was observed in 14 of 17 patients on maintenance lithium.
• Elevated basal TSH levels were found in only three patients.
• Two of these three patients exhibited clinical and biochemical hypothyroidism with delayed H.P.T. function recovery after lithium cessation.

Conclusions:

• Lithium carbonate treatment is associated with altered H.P.T. axis regulation, indicated by exaggerated TSH responses.
• A subset of patients on lithium may develop hypothyroidism.
• Monitoring of thyroid function is crucial for patients receiving lithium carbonate therapy.