Hyperparathyroidism, hypothyroidism, and impaired renal function after 10 to 20 years of lithium treatment

Of 19 patients who had been receiving a therapeutic dosage of lithium carbonate for 10 to 20 years, 8 (42%) were found to have some laboratory evidence of hyperparathyroidism. Of the 3 who had parathyroid surgery, 2 had hyperplasia and 1 had a solitary adenoma, an unusually high incidence of hyperparathyroidism. Unusual features of lithium-induced hyperparathyroidism in this series include (1) low urinary calcium excretion and the absence of nephrolithiasis, (2) normal urinary cyclic adenosine monophosphate excretion, and (3) normal plasma inorganic phosphate. Eight patients (42%) required treatment for hypothyroidism. Three patients (16%) had impaired kidney function. While these observations do not contraindicate the continued use of lithium carbonate in manic depression, they strongly emphasize the need for close laboratory surveillance.