Evaluation of parathyroid function and mineral metabolism in psychiatric patients using lithium salts

Objective: To evaluate parathyroid function and mineral metabolism in psychiatric patients users of lithium salts. Materials and methods: We measured the serum levels of calcium, ionized calcium, inorganic phosphorus, alkaline phosphatase, albumin, parathyroid hormone (PTH), urea, creatinine, 25-hydroxy-vitamin D and lithium of 35 patients diagnosed with bipolar disorder in use of lithium carbonate (LC) for at least one year (Lithium Group – LG) and 35 healthy subjects (Control Group – CG). Results: The LG and CG were matched by sex and age. There was only statistic difference in relation to the levels of PTH and ionized calcium, with p < 0.004 and p < 0.03, respectively. Secondary form of hyperparathyroidism (HPT) was found in eight (22.8%) LG patients and in none of the CG. There was no correlation between lithemia, usage time and dosage of LC. Conclusion: Our data demonstrate that lithium may create an imbalance in the parathyroid axis, characterized by elevated levels of PTH.