title: Low BMI and low TSH value as risk factors related to lower bone mineral density in postmenospausal women under levothyroxine therapy for differentiated thyroid carcinoma.
abstract: OBJECTIVE
  Treatment of differentiated thyroid carcinoma (DTC) includes suppression of TSH with levothyroxine therapy, which may negatively influence bone mineral density (BMD), but the effects are controversial. We aimed to evaluate the relationship between TSH-suppressive therapy and BMD in postmenopausal women with DTC.
  
  
  METHODS
  Cross-sectional study that assessed BMD by densitometry and risk factors for decreased BMD in 109 postmenopausal women under TSH-suppressive therapy for DTC, compared to an age-matched euthyroid women control group. Conditions that might have affected BMD were exclusion criteria.
  
  
  RESULTS
  Patients were 58.4 ± 8.3 years-old, mean serum TSH was 0.21 ± 0.28μIU/ml. In BMD evaluation, T-scores were -1.09 ± 1.43 SD (lumbar spine) and -0.12 ± 1.18 SD (total femur). No significant differences were found between lumbar or femoral T-scores of patients and control group. Multivariate logistic regression analysis evidenced that low BMI and low mean TSH levels (assessed in the year of BMD measurement) were factors significantly related to lower lumbar and spinal BMD.
  
  
  CONCLUSIONS
  Although low TSH levels and low BMI were correlated with lower BMD, it was not observed an increased prevalence of osteopenia or osteoporosis in this cohort of post-menopausal women under levothyroxine treatment for DTC, when compared to age-matched control women. Nevertheless, such risk factors should be carefully observed in individual patients at high risk of decrease in BMD.
authors.affiliation: Division of Endocrinology, Internal Medicine Department, University of Campinas, Campinas, Brazil.
authors.forename: Thaís Gomes
authors.initials: TG
authors.lastname: de Melo
authors.affiliation: Division of Endocrinology, Internal Medicine Department, University of Campinas, Campinas, Brazil.
authors.forename: Lígia Vera Montalli
authors.initials: LV
authors.lastname: da Assumpção
authors.affiliation: Division of Nuclear Medicine, Radiology Department, University of Campinas, Campinas, Brazil.
authors.forename: Allan de Oliveira
authors.initials: Ade O
authors.lastname: Santos
authors.affiliation: Division of Endocrinology, Internal Medicine Department, University of Campinas, Campinas, Brazil.
authors.forename: Denise Engelbrecht
authors.initials: DE
authors.lastname: Zantut-Wittmann
keywords: Bone mass index; Bone mineral density; Thyroid cancer; Thyrostimulating hormone