Concomitant autoimmune thyroiditis and primary hyperparathyroidism – random association? Two cases report

Abstract

Autoimmune thyroiditis and primary hyperparathyroidism are frequent diseases, mainly affecting postmenopausal women. The association between the two pathologies has been described in the literature but the underlying mechanism is not yet elucidated. We present two female patients with autoimmune thyroiditis who developed primary hyperparathyroidism. Both had normal thyroid function, high antithyroid antibodies, and high PTH and calcium values. Thyroid ultrasonography and 99mTc-MIBI scintigraphy localized the lesion but only one patient underwent surgery. Vitamin D and selenium values were normal or slightly reduced. Both patients had osteoporosis, treated with bisphosphonates. Their evolution is, till now, satisfactory. More theories are trying to explain the correlation between autoimmune thyroiditis and primary hyperparathyroidism: the inflammatory process, the high TSH or PTH values, high calcium, low vitamin D. The possible selenium intervention would correlate environmental and genetic factors. However, all these theories are controversial and not yet proved by experimental or randomized clinical studies.