Endocrine Abstracts

Background: Collagen, whose biosynthesis is regulated by thyroid hormones, is the most abundant connective tissue protein. Ehlers–Danlos syndrome alters collagen structure, which may affect bone mineral density (BMD). The purpose of this study was to assess the effect of autoimmune thyroiditis on BMD in females with Ehlers–Danlos syndrome.

Material and methods: The study involved a prospective assessment of 30 female patients, aged 20–53 years, with either hypermobile or classical Ehlers–Danlos syndrome. All patients underwent thyroid function tests, calcium and phosphorus metabolism tests, and BMD scans of the femoral neck and lumbar spine. Patients were divided into two groups: those with no autoimmune thyroiditis (group 1, n=24) and those with autoimmune thyroiditis (group 2, n=6).

Results: Study groups 1 and 2 showed no significant differences in terms of hypothyroidism (n=4 (16.7%) vs n=2 (33.3%), P=0.39), thyroid-stimulating hormone (TSH) levels (2.06 ±1.16 µIU/ml vs 2.35±2.16 µIU/ml, P=0.59), free triiodothyronine levels (3.43±0.64 pg/ml vs 3.19±0.72 pg/ml, P=0.42), or free thyroxine levels (1.35±0.25 ng/dl vs 1.34±0.12 ng/dl, P=0.44), respectively. Moreover, no significant differences were noted in bone turnover markers, such as bone-specific alkaline phosphatase (9.89±2.88 µg/l vs 8.1±0.81 µg/l, P=0.19), beta-crossLaps (0.411±0.19 ng/ml vs 0.3±0.15 ng/ml, P=0.2), and osteocalcin (21.32±7.82 ng/ml vs 17.62±4.76 ng/ml, P=0.34), or in the BMD of the femoral neck (0.93±0.12 vs 0.96±0.15, P=0.59) or lumbar spine (0.95±0.12 vs 0.94±0.17, P=0.98). Furthermore, no significant correlation was observed between the levels of TSH, anti-thyroperoxidase autoantibodies, or anti-thyroglobulin antibodies on one hand and femoral neck BMD on the other (r_s 0.09, P=0.61; r_s 0.1, P=0.59; and r_s -0.03, P=0.89, respectively) or between any of those three markers and lumbar BMD (r_s 0.11, P=0.56; r_s 0.02, P=0.93; and r_s -0.03, P=0.84).

Conclusions: This study showed no relationship between autoimmune thyroiditis, bone turnover markers, and the BMD of either the femoral neck or the lumbar spine in women with Ehlers–Danlos syndrome.