Effect of combined treatment with calcitonin on bone densitometry of patients with treated hypothyroidism.

INTRODUCTION Thyroid hormones (TH) may affect bone metabolism and turnover, inducing a loss of bone mass among hyperthyroid and in hypothyroid patients under hormone replacement treatment. Thyroid dysfunction leads to changes in the dynamics of parathyroid hormone (PTH) and calcitonin (CT) secretion. OBJECTIVE The objective of the study was to determine the usefulness of CT as adjuvant therapy in the prevention of bone loss during the treatment of hypothyroidism. MATERIAL AND METHODS We studied 16 female patients with recently diagnosed primary hypothyroidism, divided into two groups: group G1 (n = 8) submitted to treatment with thyroxine (L-T4), and Group 2 (n = 8) that, in addition to being treated with L-T4, received a nasal CT spray. All patients were submitted to determination of TSH, free T4, bone mineral densitometry (BMD) and total bone calcium (TBC) at the time of diagnosis, after 6 to 9 months of treatment, and after 12 months of treatment. RESULTS No statistical significant differences were detected in either group between the total BMD values obtained for the femur and lumbar spine before and after treatment. However, group G1 presented a statistical significant TBC loss after 12 months of treatment compared to initial values. In contrast, no TBC loss was observed in the group treated with LT-4 in combination with CT, a fact that may suggest that CT was responsible for the lower bone reabsorption during treatment of hypothyroidism.