Fracture risk lower for adults with hypoparathyroidism after thyroidectomy
Click Here to Manage Email Alerts
Key takeaways:
- Postoperative hypothyroidism after total thyroidectomy is associated with reduced risk for fractures.
- Parathyroid function was not linked to a difference in risk for hip, humerus or wrist fractures.
Adults with postoperative hypoparathyroidism after thyroid cancer are less likely to sustain a fracture compared with those with preserved parathyroid function, according to findings published in the Journal of Bone and Mineral Research.
“This result suggests that the relatively low bone turnover caused by postoperative hypoparathyroidism and appropriate management of postoperative hypoparathyroidism with active vitamin D and calcium may prevent the deterioration of skeletal health in thyroid cancer patients who can easily be exposed to long-term overtreatment with levothyroxine,” Young-Kyun Lee, MD, PhD, professor in the department of orthopedic surgery at Seoul National University Bundang Hospital and Seoul National University College of Medicine in South Korea, and colleagues wrote.
Researchers conducted a retrospective cohort study of 115,821 adults aged 18 years and older who underwent a total thyroidectomy for newly diagnosed thyroid cancer from 2008 to 2016 (83.9% women). Data were obtained from the Korea Central Cancer Registry and Korean National Health Insurance Service. Adults were defined as having postoperative hypoparathyroidism if they received at least three 90-day prescriptions for vitamin D within 1 year of thyroidectomy. Fractures were identified using ICD-10, procedure and radiographic codes. Follow-up continued until first fracture, death, censored data or the end of the study period on Dec. 31, 2017.
Of the cohort, 7.6% had postoperative hypoparathyroidism, and the rest had preserved parathyroid function. Mean follow-up was 4.6 years with postoperative hypoparathyroidism and 4.8 years with preserved parathyroid function. There were 159 fractures in the hypoparathyroidism group and 2,390 in the preserved parathyroid group. The incidence rate of any fracture was 3.9 per 1,000 person-years with postoperative hypoparathyroidism and 4.6 per 1,000 person-years with preserved parathyroid function.
Adults with postoperative hypoparathyroidism had a lower risk for sustaining any fracture than adults with preserved parathyroid function (HR = 0.83; 95% CI, 0.7-0.98; P = .037). There was no difference in risk for hip, humerus and wrist fractures between the groups. The postoperative hypoparathyroidism group had a lower risk for vertebral fractures than the preserved parathyroid function group (HR = 0.67; 95% CI, 0.47-0.96).
A higher risk for fractures also was found for older adults, women, and those who had a higher modified Charlson Comorbidity Index score, received a higher mean daily dose of levothyroxine, had bone mineral density measurements performed and received a prescription of osteoporosis medication.
In subgroup analysis, a significant interaction with the relationship between postoperative hypoparathyroidism and the risk for any fracture was observed for adults who had BMD measurements performed (P = .01) and for those who did not take calcium supplements (P = .017).
“The decrease in the risk of fractures in thyroid cancer patients with postoperative hypoparathyroidism in this study was somewhat counterintuitive in light of the previously known changes in bone metabolism in chronic hypoparathyroidism,” the researchers wrote. “This finding could be explained by the relatively shorter duration of follow-up in our study compared with previous investigations that have shown a higher risk of fractures in nonsurgical hypoparathyroidism patients compared with the general population. Although the mean follow-up duration in our study was 4.8 years, previous studies on nonsurgical hypoparathyroidism have reported follow-up periods of around 8 to 9 years.”
Collapse
Read more about
Click Here to Manage Email Alerts