Source: Head & Neck  |  Posted 10 years ago

Levothyroxine treatment is associated with femur fracture and may contribute to fracture risk in male patients.

"Levothyroxine sodium is widely prescribed and has been implicated as a cause of reduction in bone mineral density and, therefore, suggested to be a major contributor to the risk of osteoporotic fractures," explain investigators from the Departments of Medicine and Statistics at the University of Birmingham, Birmingham, England.

In order to assess potential increased fracture risk due to levothyroxine treatment, the investigators conducted a population-based, case-control analysis.

The United Kingdom General Practice Research Database was used to identify 23,183 patients on long-term thyroid hormone therapy. Four controls matched for age, sex, primary care practice and duration of registration on the database were identified for every patient prescribed levothyroxine.

The number of patients who had proximal femur fractures was determined as were any drug therapies and medical diagnoses that could influence fracture risk were assessed.

Overall, 1.61 percent of the patients prescribed thyroid hormone sustained fractures of the femur compared with 1.44 percent of the controls.

Rate of fracture was significantly different between male patients taking levothyroxine and male controls. Levothyroxine was found to be an independent predictor of fracture occurrence in males but not females.

The investigators point out that patients taking levothyroxine had higher rates of medical diagnoses and therapies, which could confound the fracture risk.

"The lack of association between fracture and levothyroxine prescription in the whole cohort is reassuring," the investigators conclude, "although an independent association between levothyroxine prescription and fracture occurrence in male patients suggests that levothyroxine may contribute to fracture risk in this specific group."