Objective: To clarify the association between treatment of affective psychiatric disorders with lithium, and the development of secondary hyperparathyroidism.
Design: Retrospective review of medical records, 1973-89.
Subjects: 17 patients with affective psychiatric disorders who were treated with lithium (n = 6) or with tricyclic antidepressant, or neuroleptic, drugs (n = 11) all of whom were operated on for hyperparathyroidism.
Main outcome measure: Duration of lithium therapy and parathyroid histology.
Results: Parathyroid hyperplasia was present in 5 patients who had taken lithium during a median period of 13 years. A parathyroid adenoma was found in one patient treated with lithium for three years. Ten of the 11 patients who had been treated with tricyclic antidepressant, or neuroleptic drugs had a parathyroid adenoma and the remaining one had an adenoma as an underlying cause of hyperparathyroidism.
Conclusion: Hyperparathyroidism in patients who have undergone long term treatment with lithium is associated with parathyroid hyperplasia. This indicates that lithium may exert a chronic stimulus that results in secondary hyperparathyroidism.