SUN-412 Graves’ Disease Displayed as a Risk Factor of Vertebral Fracture Even in Premenopausal Women

Background Hyperthyroidism is a known risk factor for osteoporosis and fractures especially in older men and postmenopausal women. However, it remains unclear whether younger patients with Graves’ diseases are at a higher risk of fracture compared to healthy individuals. Objective This study aimed to clarify whether premenopausal women with Graves’ disease represents a risk factor for vertebral fracture (VF). Patients and Methods We enrolled 30 premenopausal women (mean age, 32 ± 10 years) who were diagnosed with Graves’ disease at our institution between April 2007 and December 2017. We also enrolled 40 healthy control women who visited our hospital. The control subjects were confirmed to have no endocrine disease or any condition that might affect bone metabolism. None of the study subjects had taken drugs known to influence bone and calcium metabolism such as vitamin D, bisphosphonates, or glucocorticoids. Also, none has taken an oral contraceptive. Serum and urinary biological parameters, alkaline phosphatase (ALP), glycosylated hemoglobin (HbA1c), creatinine, serum calcium, total cholesterol, intact parathyroid hormone, free triiodothyronine (Free T3), free thyroxin (Free T4), thyroid-stimulating hormone (TSH) and urinary type I collagen cross-linked N-telopeptides (NTX; a bone resorption marker) were compared between the groups. Bone mineral density (BMD) of the lumbar spine and femoral neck was determined using dual-energy X-ray absorptiometry and vertebral fractures were diagnosed from lateral X-rays of the thoracic and lumbar spine. The chi-square and unpaired t-tests for two groups comparison were utilized to determine the statistical significance (P < 0.05). Multiple logistic regression analyses were proceeded after adjustments for variables. Results Patients with Graves’ disease displayed the higher ALP, eGFR, Ca, free T3, free T4 and urinary NTX levels, and lower body mass index (BMI), Alb, total cholesterol and intact PTH compared to controls. The prevalence of VFs was significantly higher in patients with Graves’ disease (20.0%) than in controls (2.5%, <0.05). Such association remained significant even after adjustment for age, BMI, ALP, eGFR and free T3, but except for BMD. Among premenopausal patients with Graves’ disease, the values of several parameters, such as BMI, ALP, HbA1c, serum Ca, intact PTH and BMD and the prevalence of thyroid related antibodies did not differ significantly between those with and without VF; subjects with VF were older and exhibited lower free T3, free T4 and urinary NTX levels compared to subjects without VF. The mean value of lumbar BMD T score in subjects with VF among premenopausal patients with graves’ disease was -1.0, indicating osteopenia. Conclusions VF risk could be elevated even in the premenopausal women with Graves’ disease, although the BMD risk levels is not equivalent to that of osteoporosis.