Low Normal TSH levels are Associated with Impaired BMD and Hip Geometry in the Elderly

Abstract

Subclinical hyperthyroidism is known to be associated with the risk of fractures in elderly people. However, there are few studies assessing whether low normal thyroid-stimulating hormone (TSH) levels affect bone density and geometry. Here, we aimed to assess the influence of the TSH level on bone mineral density (BMD) and geometry in elderly euthyroid subjects. This was a cross-sectional cohort study. A total of 343 men and 674 women with euthyroidism were included and analyzed separately. The subjects were divided into tertiles based on the serum TSH level. The BMD and geometry were measured using dual-energy X-ray absorptiometry and a hip structural analysis program. Multiple regression analysis was used to compute the odds ratios of osteoporosis in the lower TSH tertile group and the association between geometry parameters and the TSH level. We found that the femoral neck and total hip BMDs were lower in the lower TSH tertile group. In women, the cross-sectional area and cortical thickness of the femur were negatively associated with the TSH level in all three regions (the narrow neck, intertrochanter, and femoral shaft); however, in men, these geometry parameters were significantly associated with the TSH level only in the intertrochanter region. The buckling ratio, a bone geometry parameter representing cortical instability, was significantly higher in the lower TSH tertile group in all three regions in women, but not in men. Our results indicated that lower TSH levels in the euthyroid range are related to lower BMD and weaker femoral structure in elderly women.Key words: TSH, euthyroidism, elderly people, bone density, bone geometry Maintaining normal thyroid function is important for achieving appropriate bone development and peak bone mass in young age, as well as for regulating the rate of bone turnover in adults [1]. It is well known that bone mineralization is reduced and that the rate of bone turnover is increased in thyrotoxicosis [1][2][3], leading to an increased risk of hip fractures [4,5]. Bauer et al. showed an association between low thyroid-stimulating hormone (TSH) levels and hip fractures in subclinical hyperthyroidism [6] and a recent meta-analysis [7] revealed increased fracture risk in cases of subclinical hyperthyroidism. Moreover, Murphy et al. reported that higher free thyroxine (fT4) levels were associated with reduced hip bone mineral density (BMD), even in

Cohort profile: Korean Urban Rural Elderly (KURE) study, a prospective cohort on ageing and health in Korea

“…In this cohort, we found independent and additive association of red blood cell distribution width with morphometric vertebral fracture 29. A low thyroid-stimulating hormone level reflecting subclinical thyrotoxicosis was associated with low bone mass and impaired hip geometry 30. In overall, we sought to establish the value of newly emerging concept, dysmobility syndrome and novel biomarkers of musculoskeletal health in this cohort, which need to be continued in further studies.…”

Actions of pituitary hormones beyond traditional targets

“…The National Health and Nutrition Examination Survey (NHANES) has further shown that the odds ratio for correlations between TSH and bone mass ranged between 2 and 3.4 (Morris 2007). Elderly women with low-normal TSH levels (in the euthyroid range) have lower BMDs with or without weaker femoral structures (Ding, et al 2016; Lee, et al 2016). Such women also have a high vertebral fracture risk, independent of age, BMD and thyroid hormones (Mazziotti, et al 2010).…”

Thyroid disease in the elderly

“…To obvykle odhalí uzlovou přestavbu, následná scintigrafie přítomnost independentního adenomu nebo uzlovou přestavbu s oblastmi zvýšené aktivity. Zjištění těchto změn ve ŠŽ je podporou při rozhodování o léčbě, zvláště při fibrilaci či jiném typu dysrytmie nebo při průkazu zvý šeného kostního obratu [24]. Subklinická hypertyreóza by měla být léčena především u starších osob [25,26], podáváme tyreostatika v dávce, která normalizuje TSH, ev.…”

“…Dle současných názorů supresní léčba u ne rizikových osob postačí maximálně 5 let. Dlouhodobá suprese je rizikem pro rozvoj osteoporózy [24].…”