This article is more than 5 years old. Information may no longer be current.
TSH, free T4 levels tied to hip fracture risk
Click Here to Manage Email Alerts
The risk for hip fracture may increase with low thyroid-stimulating hormone levels and high free thyroxine levels in euthyroid adults, according to findings published in The Journal of Clinical Endocrinology & Metabolism.
Nicolas Rodondi, MD, MAS, of the department of general internal medicine at Bern University Hospital in Switzerland, and colleagues evaluated data from 13 large prospective cohorts with baseline examinations between 1981 and 2002 on 61,959 adults (mean age, 64 years; 60.5% women) with euthyroidism to determine the association of TSH and free T4 with incident fracture. Follow-up was a median 12.1 years for 659,059 person-years; median TSH was 1.6 mIU/L. At baseline, 3.1% of participants were prescribed thyroid medications compared with 5.5% during follow-up. Participants were divided into groups based on TSH levels: 0.45 mIU/L to 0.99 mIU/L (17.7%), 1 mIU/L to 1.49 mIU/L (24.8%), 1.5 mIU/L to 2.49 mIU/L (37.4%), 2.5 mIU/L to 3.49 mIU/L (14.2%) and 3.5 mIU/L to 4.49 mIU/L (5.9%; reference group). Overall, 4.5% of participants had a hip fracture occur, 8.9% had any fracture, 8.5% had a nonvertebral fracture and 1.3% had a vertebral fracture.
The pooled age- and sex-adjusted HR for hip fracture was 1.25 (95% CI, 1.05-1.49) for TSH 0.45 mIU/L to 0.99 mIU/L, 1.19 (95% CI, 1.01-1.41) for TSH 1 mIU/L to 1.49 mIU/L, 1.09 (95% CI, 0.93-1.28) for TSH 1.5 mIU/L to 2.49 mIU/L and 1.12 (95% CI, 0.94-1.33) for TSH 2.5 mIU/L to 3.49 mIU/L compared with the reference group. Compared with the reference group, the HR was 1.24 (95% CI, 1.03-1.49) for TSH 0.45 mIU/L to 0.99 mIU/L after adjustment for BMI, smoking status and history of diabetes. The risk for hip fracture was significantly higher in participants with TSH levels 0.45 mIU/L to 0.99 mIU/L compared with the other groups in all sensitivity analyses, except after adjustment for femoral neck bone mineral density or after exclusion of participants with thyroid-altering medication at baseline. Per one standard deviation increase in free T4, the HR for hip fracture was 1.24 (95% CI, 1.12-1.37).
Overall, 25,760 participants had available data on thyroid function tests during follow-up; 0.6% developed subclinical hyperthyroidism, and 0.2% developed overt hyperthyroidism.
“Clinicians should be aware that lower TSH and higher [free] T4 levels, even among adults with euthyroidism, are associated with an increased risk of hip fracture,” Rodondi told Endocrine Today. “Other risk factors for fracture or osteoporosis should be particularly assessed among these adults. Further studies in adults with euthyroidism are needed to assess the association of extreme values of TSH or [free] T4 within the currently defined reference range with adverse health outcomes.” – by Amber Cox
For more information:
Nicolas Rodondi, MD, MAS, can be reached at Department of General Internal Medicine, Inselspital, Bern University Hospital, University of Bern, 3010 Bern, Switzerland; email: Nicolas.rodondi@insel.ch.
Disclosure: The researchers report no relevant financial disclosures.
Click Here to Manage Email Alerts