Abstract 109: Subclinical thyrotoxicosis and bone mineral density in pre-menopausal women

Background: Subclinical thyrotoxicosis is a condition in which serum thyroid hormone levels are within the reference range, but serum thyrotropin (TSH) levels are subnormal. It is not known whether differences in patterns of thyroid hormone levels between endogenous and exogenous subclinical thyrotoxicosis result in disparate effects on the skeletal system. There is a paucity of data on patients with subclinical thyrotoxicosis and their bone health status. Objectives: To estimate bone mineral density in patients with subclinical thyrotoxicosis in patients due to different aetiologies in premenopausal women. Methods: This cross-sectional study was conducted at Ramaiah medical college for a period of one year. A total of twenty-six patients were included. Demographical data was analysed by descriptive statistics and expressed as mean with standard deviation. Bone mineral density was measured by hologic v2.0. Results: A total of 26 individuals were included in the study. The mean age of the study population was 34.2 ± 8.1 years. The etiology for subclinical thyrotoxicosis was Graves' disease in 11 (42.3%), multi-nodular goiter 4 (15.3%), toxic adenoma 3 (11.6%), and iatrogenic in 8 (30.7%) patients. The mean BMI was 25.8 ± 7.2 kg/m2. The mean corrected calcium was 9.15 ± 0.26 mg/dl and phosphorus was 2.98 ± 0.36 mg/dl. The mean 25 hydroxy vitamin D level was 30.3 ± 4.41 ng/dl. Mean BMD at hip and spine was 0.96 ± 0.14 g/cm2 and 0.90 ± 0.06 g/cm2 respectively. No patient had a Z score of <-2 S.D in the hip and spine. The mean Z score at the hip and spine was +0.55 ± 0.88 and +0.22 ± 0.75 respectively. There was no significant difference between the endogenous and exogenous etiology subgroup in BMD at the hip or spine [p = 0.668 CI (-0.0629 - 0.0429)] and [p = 0.604 CI (-0.0879 - 0.1479)]. Conclusion: There was no significant reduction in bone mineral density at the hip or spine as measured by DXA in our cross-sectional study of premenopausal women with subclinical thyrotoxicosis of both endogenous and exogenous etiology. In young females with adequate serum25 hydroxy-vitamin Dlevels, endogenous subclinical thyrotoxic state may not have a deleterious effect on bone health in the short term.