Abstract

Background: Studies on bone mineral density (BMD) disorders associated with hypothyroidism are inadequate. The effects of thyroid hormone therapy on BMD in primary hypothyroidism have been different. This study aimed to determine the severity of osteoporosis in patients with hypothyroidism compared with healthy women. Methods: This descriptive, analytical study was conducted on women who were referred to Alzahra Hospital (Isfahan, Iran) during 2011. A total number of 150 subjects were divided into 3 groups of 50. Group A had been recently diagnosed with primary hypothyroidism. Group B included patients with primary hypothyroidism who had at least received levothyroxine for 2 years. Group C consisted of healthy individuals who were used as controls. After obtaining consents, bone densitometry was performed. Data was collected using a checklist including age, weight, height, body mass index (BMI), age at menopause, duration of levothyroxine administration (if used), severity of osteoporosis based on densitometry, and serum thyroid stimulating hormone (TSH). Data was analyzed by regression analysis, Kruskal-Wallis and Mann-Whitney tests, and analysis of variance (ANOVA). P values less than 0.0.5 were considered significant. Findings: The mean age, TSH levels, and T scores of lumbar vertebrae (L2-L4) in group B were significantly lower than the other two groups (P < 0.01, P < 0.05, and P < 0.05, respectively). There was no relation between osteoporosis and TSH levels. However, after adjustment for TSH, frequency of osteoporosis was significantly higher in group B (P < 0.05). Conclusion: Although patients newly diagnosed with hypothyroidism (group A) had significantly higher TSH levels, there was no significant difference between them and controls in bone density of lumbar spine and femoral neck. Since patients who had used levothyroxine for at least 2 years had lower TSH and bone density compared to the control group, treatment of low bone mass in patients with hypothyroidism is necessary.