Endocrine effects of lithium: II. 'Primary' hyperparathyroidism

Area of Science:

• Endocrinology
• Psychiatry
• Pharmacology

Background:

• Lithium is a common mood stabilizer for bipolar disorder.
• Long-term lithium use has been associated with various metabolic disturbances.
• The specific impact on parathyroid hormone and mineral levels requires further elucidation.

Purpose of the Study:

• To investigate the effects of long-term lithium treatment on parathyroid hormone, calcium, and magnesium levels in patients with manic-depressive illness.
• To determine the prevalence and characteristics of hyperparathyroidism in this patient group.

Main Methods:

• A cohort of 96 patients with manic-depressive illness undergoing long-term lithium treatment was studied.
• Serum levels of immunoreactive parathyroid hormone, calcium, and magnesium were measured.
• Serum phosphate and alkaline phosphatase levels were also assessed.

Main Results:

• Significant elevations in serum immunoreactive parathyroid hormone were observed (P < 0.001).
• Protein-corrected serum calcium and serum magnesium levels were also significantly increased (P < 0.001).
• Patients exhibited normophosphatemia and normophosphatasia, suggesting mild biochemical hyperparathyroidism.

Conclusions:

• Long-term lithium treatment is associated with a state of primary hyperparathyroidism in manic-depressive patients.
• The observed biochemical changes indicate a mild form of hyperparathyroidism.
• These findings highlight the importance of monitoring parathyroid function in patients on long-term lithium therapy.