& Aging Musculosekeletal Disorders Page 1 of 4 Short c ommunication Thyroid and bone fragility J Callear 1 , WK Jerjes 1 *, HB Tan 1 , PV Giannoudis 1 Abstract The hypothalamic-pituitary-thyroid sweating, tremor and weight loss. Introduction axis is a classical negative feedback The main biochemical feature is a This short communication seeks to loop. It is important for the synthesis decreased TSH level, usually with a highlight the link between thyroid dis- and secretion of thyroid hormones concurrent increase in free serum T4. ease and bone fragility. namely thyrotropin releasing hor- T3 is raised in 1% of patients with Short Communication mone (TRH), thyroid stimulating hor- hyperthyroidism 3,4 . Bone remodelling/metabolism involve mone (TSH), thyroxine (T4) and The prevalence of spontaneous a homeostatic balance between forma- tri-iodothyronine (T3) 2 . hypothyroid disease is estimated at tion (osteoblastic) and resorption (ost- Low detectable levels of serum T3 between 1% and 2% in the UK. Women All authors contributed to the conception, design, and preparation of the manuscript, as well as read and approved the final manuscript. eoclastic). This balance is regulated by stimulate the paraventricular nucleus are predominantly affected, with a bone regulatory molecules, including of the hypothalamus to synthesise female:male ratio of 10:1. The aetiol- receptor activator of nuclear factor-κ B and secrete the tri-pepetide TRH. ogy of hypothyroidism can be subdi- and osteoprotegerin. TRH in turn stimulates the thyrotroph vided into primary, secondary and Conclusion cells of the anterior pituitary gland to transient. Primary causes include Elevated thyroid hormone may lead to secrete TSH. This glycoprotein acts on autoimmune disease (Hashimoto’s increased bone resorption activities, the seven transmembrane G-protein thyroiditis and atrophic thyroiditis), which may lead to an increased risk of coupled to TSH receptors (TSHR) on iodine deficiency, iatrogenic causes osteopenia and osteporotic fractures. the thyroid gland to promote the (post-thyroidectomy or radioiodine synthesis and secretion of the pro- treatment), medication induced (anti- Introduction hormone T4 and active hormone T3. thyroid medications, amiodarone and The first clinical account which linked Peripheral conversion of T4 to T3 is lithium), congenital absence of the thyroid disease with bone fragility was achieved by type 2 iodothyronine dei- thyroid gland or thyroid gland infil- reported by von Recklinghausen 1,2 . odinase enzyme (D2). D2 contributes tration by amyloidosis or sarcoidosis. The study correlated the hyperthyroid to 85% of T3 synthesis; 95% of T4 and Secondary causes include hypopitui- state with an increased risk of bone fr- T3 are primarily bound to thyroxine- tarism or hypothalamic disorder. acture. Over the subsequent 100 years, All authors abide by the Association for Medical Ethics (AME) ethical rules of disclosure. binding globulin (TBG). Uptake of Transient disease may be secondary it has become apparent that both hyp- free circulating T3 and T4 is deter- to withdrawal of thyroid medications othyroidism and hyperthyroidism are mined by three specific cell mem- or to post-partum thyroiditis 3,4 . associated with an increased risk of fr- brane transporters: monocarboxylate Typical features of hypothyroidism actures. The prevalence of hypothyroi- transporters 8, 10 and organic acid may include constipation, depression, dism and hyperthyroidism in the Unit- Competing interests: none declared. Conflict of interests: none declared. transporter protein-1c1. Intracellular decreased appetite, weight gain, dry ed Kingdom (UK) are estimated at levels of iodothyronine deiodinase skin, hoarse voice, reduced libido, thin- 1%–2% and 0.5%–2%, respectively. enzymes type 1 and 2 determine the ning and loss of hair, intolerance to cold, Females are predominantly affected activity and availability of active T3 2 . lethargy and menorrhagia. Symptoms by both of these conditions, with a fe- The prevalence of hyperthyroid dis- tend to be insidious in nature, hence male:male ratio of 10:1. The incidence ease is estimated at between 0.5%–2% patients often present late to healthcare increases with age; therefore, in an ag- in the UK. Primary causes include services. In the post-partum woman eing population, thyroid dis-ease shou- Graves’ disease (an autoimmune IgG- and the elderly, hypothyroidism can ld be considered in all individuals pre- mediated condition), toxic nodular be commonly misdiagnosed and the senting with fractures 3 . goitre or a solitary thyroid nodule. symptoms attributed to other illnesses. Secondary causes include de Quervain Treatment of hypothyroidism is with thyroiditis, carcinoma of the thyroid levothyroxine, starting at 25 µg/24 h gland and over-treatment with thyroid and subsequently increasing according medications. Typical clinical presenta- to the response. Close monitoring is * Corresponding author tions of hyperthyroidism may include recommended, initially at 12-weekly Email: waseem_wk1@yahoo.co.uk anxiety, oligo- or amenorrhoea, diar- and then at 6-weekly intervals, to 1 Academic Unit of Trauma and Orthopaedic rhoea, irritability, fatigue, increased ap- ensure TSH > 0.5 mU/L. Thus strict Surgery, School of Medicine, University of petite, intolerance to heat, restlessness, surveillance is recommended as early Leeds, Leeds, United Kingdom. Licensee OA Publishing London 2012. Creative Commons Attribution License (CC-BY) F�� �������� ��������: C allear J, Jerje s WK, T an HB, Giannoudis PV. Thyroid and bone fragility. Hard Tissue. 2012 Nov 10;1(1):7.
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