CO-EXISTING HASHIMOTO'S THYROIDITIS DOES NOT AFFECT BONE METABOLISM IN PATIENTS WITH PRIMARY HYPERPARATHYROIDISM.

CONTEXT: Primary hyperparathyroidism (PHPT) is often associated with thyroid disorders like nodular goiter, Hashimoto's thyroiditis (HT) and Graves' disease.

OBJECTIVE

Our aim was to explore whether the co-existence with HT affects bone metabolism in patients with PHPT.

DESIGN

This was a comparative cross-sectional study carried out in a tertiary inpatient endocrine center from January 2018 through December 2020.

SUBJECTS AND

METHODS

A total of 234 patients were diagnosed with PHPT at our endocrine center. One hundred of them were included in the study - 50 with PHPT only and 50 with PHPT and HT. Two control groups were defined: 37 with HT and 37 without PHPT and HT. Serum markers of calcium-phosphate metabolism, bone markers (RANKL, Osteoprotegerin, β-CTX, Osteocalcin) and interleukin-17A were measured.

RESULTS

The frequency of HT among patients with PHPT was 37.6% (95% CI 31-43%) and did not differ significantly from that in the general population, 32.5% (95% CI 30-35%). Age, BMI, markers of calcium-phosphate metabolism, bone markers and interleukin-17A weren't significantly different in PHPT with and without HT or between the two control groups. The participants with PHPT had higher levels of interleukin-17A, β-CTX and Osteocalcin (p<0.05) than those without the PHPT. RANKL and Osteoprotegerin in these groups did not differ.Interleukin-17A correlated positively with serum calcium, PTH and RANKL and negatively with serum inorganic phosphate and 25(OH)D. Controlling for HT and age did not change the correlation.

CONCLUSIONS

In our study, HT has not additional effect on bone metabolism in the patients with PHPT. Higher levels of interleukin-17A in PHPT suggest a possible role in the PTH-induced bone remodeling.