A prospective study of thyroid function, bone loss, and fractures in older men: The MrOS study

Abstract

Excess thyroid hormone is associated with increased bone loss and fracture risk in older women, but few data exist in men. We sought to determine if thyroid function is independently associated with bone loss and fracture risk in older men. Data were analyzed from the Osteoporotic Fractures in Men (MrOS) Study, a cohort of community-dwelling US men aged 65 years and older. Using a case-cohort design, fasting baseline serum archived at −80C was assayed for thyrotropin (TSH) and free thyroxine (FT4) in 397 men with confirmed non-spine fracture, including 157 hip fractures, and 1420 randomly selected men without fracture. TSH and FT4 were analyzed as continuous variables and as thyroid function categories (subclinical hyperthyroid, euthyroid, and subclinical hypothyroid). Hip DXA (Hologic QDR4500) was measured at baseline and after a mean follow-up of 4.6 yr. Incident nonspine fractures were centrally adjudicated. Bone loss was evaluated with multivariate regression methods and fractures risk was evaluated using hazard models that accounted for the case-cohort sampling, adjusted for age, clinic-site, BMI, race, physical activity, corticosteroid use, smoking, alcohol intake, and thyroid medication use. In fully adjusted analyses, TSH was not associated with risk of nonspine fracture (RH 0.92 per SD decrease in TSH, 95% CI 0.74 – 1.14), but was significantly associated with risk of hip fracture (RH 1.31 [1.01 – 1.71]) which persisted among normal range TSH values (RH 1.21 [1.00 – 1.47]). There was no association between TSH or FT4 and bone loss, and fracture risk did not differ significantly by thyroid function category. We conclude that while neither TSH nor FT4 are associated with bone loss, lower serum TSH may be associated with an increased risk of hip fractures in older men.

Does thyroid function influence fracture risk? Prospective data from the HUNT2 study, Norway

“…Albeit often used in epidemiologic studies, self-reporting is less reliable than laboratory measurements (37). Most studies report hyperthyroidism to be a risk factor for fractures (6,7,8,9,11,12), and even subclinical hyperthyroidism has been associated with increased fracture risk (13,14). Moreover, studies have reported increased fracture risk related to hypothyroidism (6,10,12) as well as to differences in thyroid function within the reference range (13,17,18).…”

“…Most studies report hyperthyroidism to be a risk factor for fractures (6,7,8,9,11,12), and even subclinical hyperthyroidism has been associated with increased fracture risk (13,14). Moreover, studies have reported increased fracture risk related to hypothyroidism (6,10,12) as well as to differences in thyroid function within the reference range (13,17,18). However, especially outside the hyperthyroid range, no relation between levels of thyroid function and fracture risk has also frequently been reported (7,13,14,20), and there is even one study where self-reported previous hyperthyroidism appeared to decrease foot fracture risk (19).…”

“…Hypothyroidism is a risk factor for falls in elderly individuals (4), and hyperthyroidism has for more than a century been known as a risk factor for osteoporosis (5). Both overt hypothyroidism and hyperthyroidism have been associated with increased risk of fractures in previous studies (6,7,8,9,10,11,12,13,14). Other studies have reported that fractures are more common in persons with subclinical thyroid dysfunction (15,16), and some have found fracture incidence to increase by decreasing thyroid-stimulating hormone (TSH) within the reference range (13,17,18).…”

“…Both overt hypothyroidism and hyperthyroidism have been associated with increased risk of fractures in previous studies (6,7,8,9,10,11,12,13,14). Other studies have reported that fractures are more common in persons with subclinical thyroid dysfunction (15,16), and some have found fracture incidence to increase by decreasing thyroid-stimulating hormone (TSH) within the reference range (13,17,18). However, the results of these and other studies are inconsistent (7,13,14,19,20).…”

“…Other studies have reported that fractures are more common in persons with subclinical thyroid dysfunction (15,16), and some have found fracture incidence to increase by decreasing thyroid-stimulating hormone (TSH) within the reference range (13,17,18). However, the results of these and other studies are inconsistent (7,13,14,19,20). A few studies have investigated the importance of autoimmunity in thyroid disorders for fracture risk, but the results are inconclusive (21,22).…”