Factors related to bone mineral density in female patients receiving TSH-suppressive doses of levothyroxine for thyroid cancer

Abstract

Background: Patients with thyroid cancer receive a high-dose thyroid hormone therapy after total thyroidectomy for suppression of thyroid stimulating hormone (TSH); this may affect bone mineral density (BMD). Identifying the common factors that affect BMD (including the duration of a high dose of thyroid hormone treatment) may, therefore, aid the delivery of appropriate and comprehensive care in such cases. Objective: To identify the factors related to BMD in female patients with thyroid cancer. Materials and Methods: This cross-sectional study evaluated data pertaining to the BMD and demographic characteristics of female patients with thyroid cancer. The patients were aged at least 40 years and received a high-dose thyroid hormone replacement therapy after total thyroidectomy at the Rajavithi Hospital between January 2004 and December 2019. The relationships between BMD and associated factors were analyzed using Pearson’s correlation and multiple linear regression. A p-value of less than 0.05 was considered statistically significant. Results: A total of 100 female patients with a mean age of 55.37 ± 11.36 (40-82) years and mean body mass index (BMI) of 24.8 ± 4.96 (15-40) were included; 60 and 56 of them were postmenopausal and coffee drinkers, respectively. High-dose thyroid hormone replacement therapy was received for a mean duration of 94.59±50.36 (3-210) months and 13 patients had a history of fractures; 60%, 30%, and 10% had normal BMD, osteopenia, and osteoporosis, respectively. The factors affecting BMD included the BMI (p-value <0.001) and postmenopausal status(p-value <0.001). Subgroup analyses showed the BMI to be the factor affecting BMD in the premenopausal group (p-value <0.001). Age, BMI, and calcium supplement intake were found to have an effect on the BMD in the postmenopausal group (p-value= 0.003, 0.002, and 0.020, respectively). The duration of high-dose thyroid hormone intake had no effect on the BMD in both the overall population (p-value= 0.558) and the subgroups based on the menopausal status (p-value = 0.437 and 0.380 in premenopausal and postmenopausal groups, respectively). Conclusion: In female patients who were treated for thyroid cancer, the factors affecting the BMD included the BMI in the premenopausal group and the age, BMI, and calcium supplementation in the postmenopausal group.