title: Ten-year estimated risk of bone fracture in women with differentiated thyroid cancer under TSH-suppressive levothyroxine therapy.
abstract: BACKGROUND
  After thyroidectomy and radioiodine therapy, patients with differentiated thyroid cancer (DTC) are indefinitely treated with levothyroxine (L-T4). Osteoporosis is a debated consequence of hypothyroxinaemia. The aim of this study was to evaluate bone mineral density (BMD) and fracture risk assessed by FRAX in a cohort of DTC women.
  
  
  METHODS
  Seventy-four women with DTC (aged 56.5 ± 9.9 years) treated at the mean age of 51.9 ± 12.0 years were studied. Baseline BMD and FRAX were evaluated after 3.0 years (median). BMD and FRAX were further evaluated 5.5 years (median) after the baseline evaluation. A cohort of 120 euthyroid women, matched for age, BMI, and menopausal status, were evaluated as controls.
  
  
  RESULTS
  L-T4 dosages were 813.6 ± 208.8 μg/week and 782.1 ± 184.4 μg/week at the baseline and second evaluation, respectively. The risks of major osteoporotic fracture (MOF) and hip fracture (HF) were similar in DTC patients and in controls. In DTC women, significant changes in FRAX were found, with a higher increase in the probability of HF than of MOF. A similar change was found in controls. A significant inverse correlation (P < 0.001) between L-T4 dosage and HF/MOF probability on both first and second evaluations was found. A significant inverse correlation (P = 0.05) was found between fT4, TSH and duration of therapy and HF/MOF probability only on the second evaluation.
  
  
  CONCLUSIONS
  FRAX increase is a multi-factorial, age-related phenomenon. The absence of correlations between L-T4 dosage, length of therapy or fT4 levels and FRAX does not enable us to attribute an increased fracture risk to DTC women with well-controlled disease on therapy. (Endokrynol Pol 2016; 67 (4): 350-358).
authors.forename: Lara
authors.initials: L
authors.lastname: Vera
authors.forename: Stefano
authors.initials: S
authors.lastname: Gay
authors.forename: Claudia
authors.initials: C
authors.lastname: Campomenosi
authors.forename: Sabrina
authors.initials: S
authors.lastname: Paolino
authors.forename: Giorgia
authors.initials: G
authors.lastname: Pera
authors.forename: Eleonora
authors.initials: E
authors.lastname: Monti
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Mortara
authors.forename: Bruno
authors.initials: B
authors.lastname: Seriolo
authors.affiliation: Endocrine Unit, Department of Internal Medicine, University of Genoa. magius@unige.it.
authors.forename: Massimo
authors.initials: M
authors.lastname: Giusti
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000009:adverse effects / Q000627:therapeutic use; D008875:Middle Aged; D058866:Osteoporotic Fractures / Q000175:diagnosis / Q000209:etiology* / Q000517:prevention & control; D011184:Postoperative Period; D012306:Risk; D013964:Thyroid Neoplasms / Q000188:drug therapy / Q000601:surgery*; D013965:Thyroidectomy / Q000009:adverse effects; D013974:Thyroxine / Q000008:administration & dosage / Q000627:therapeutic use*
chemical_list: D007457:Iodine Radioisotopes; D013974:Thyroxine
keywords: FRAX; bone fracture risk; hyperthyroxinemia; levo-thyroxine therapy; osteoporosis; thyroid cancer