Utjecaj tireotropnih hormona na koštani metabolizam

master's thesis

• Title (english): Effects of tireotropic hormones on bone metabolism
• Author: Vivian Milotić
• Mentor: Lovorka Grgurević (mentor)
• Committee member: Slobodan Vukičević (predsjednik povjerenstva)
• Committee member: Zdravko Petanjek (član povjerenstva)
• Committee member: Lovorka Grgurević (član povjerenstva)
• Granter: University of Zagreb; School of Medicine; (Department of Anatomy and Clinical Anatomy); Zagreb
• Defense date and country: 2014-07-15, Croatia
• Scientific / art field, discipline and subdiscipline: BIOMEDICINE AND HEALTHCARE; Basic Medical Sciences; Anatomy

Abstract

Utjecaj hormona štitnjače, kao i njihov mehanizam djelovanja predmet su istraživanja više od jednog stoljeća i još uvijek nisu do kraja razjašnjeni. Kliničke studije uzročno su povezale hipertireoidizam i povećanu učestalost fraktura, čak i nakon uspostave eutiroidnog statusa. Subklinički hipertiroidizam također utječe na koštanu gustoću, ali su podaci oko povećane incidencije prijeloma kontradiktorni. U skladu s navedenim, u pacijenata s hipotireozom primjećuje se povećana ili normalna koštana gustoća.
U pacijenata s niskom razinom tireotropina (TSH) uočen je snižen koštani volumen, dok pacijenti s TSH u granicama normale imaju koštani volumen jednak zdravim eutireotičnim osobama i posljedično nepromijenjen rizik koštanih prijeloma. Otkrićem receptora za TSH na kosti otvoreno je pitanje njegovih direktnih učinaka na koštani metabolizam bez posredovanja hormona štitnjače.
Antiresorptivni i anabolički potencijal TSH pokazan je u starih ovarijektomiranih štakora, štakora s uklonjenom štitnom i doštitnim žlijezdama te u miša s homozigotnim nul alelom za TSH receptor. Pretklinički nalazi potvrđeni su u kliničkim studijama. Pacijenti stariji od 65 godina, s niskom razinom TSH u serumu imaju veći rizik za frakturu kralješka i kuka.
Značaj učinka TSH na koštani metabolizam danas je jasan, dok je mehanizam njegova djelovanja samo djelomično objašnjen. Zaključno, koncentracija TSH trebala bi biti rutinski određena u pacijenata s povećanim rizikom za osteoporozu i poremećenim tiroidnim statusom.

Abstract (english)

The mechanisms of action as well as the clinical effects of thyroid hormones on bone has been of interest for more than a century, and are still not fully elucidated. Hyperthyroidism is associated with an increased life-time risk for fractures, even after achieving euthyroid status. Subclinical hyperthyroidism may also affect bone mineral density, while possible increase of fracture rate is not unanimously established. On contrary, hypothyroid patients tend to exhibit higher or normal bone density.
It was found that only patients with suppressed thyroid-stimulating hormone (TSH) had decreased bone volume, whereas patients with a TSH level in the normal range seem to have similar bone volume as euthyroid humans and accordingly decreased fracture rate. The presence of active TSH receptor in bone raised the possibility of its direct stimulation of bone formation without interplay with tyhroid hormones.
TSH exerts both antiresorptive and anabolic effects on bone remodeling in aged ovariectiomized rats, TSH receptor null mice and rats with removed thyroid and parathyroid glands. Moreover, patients older than 65, who had a low serum TSH level, were at increased risk for vertebral and hip fractures.
Collectively, importance of TSH in bone homeostasis is nowadays clear. Nevertheless, mechanism of TSH actions on bone is still partially unclear. TSH status should be examined in all patients with increased risk of osteoporosis accompanied with impaired thyoid status.

• Keywords: koštani metabolizam; hipertireoidizam; tireotropin
• Keywords (english): bone metabolism; hyperthyroidism; thyoid stimulating hormone
• Language: croatian
• URN:NBN: urn:nbn:hr:105:140801
• Study programme: Title: Medicine; Study programme type: university; Study level: integrated undergraduate and graduate; Academic / professional title: doktor/doktorica medicine (doktor/doktorica medicine)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2015-10-20 16:10:48