Endocrine Abstracts

Introduction: The association of primary hyperparathyroidism (PHPT) and hyperthyroidism secondary to toxic multinodular goiter (TMNG) is rarely described in the literature. Hereby, we describe the clinical, biological, and radiological characteristics of two patients having this rare association.

Observations: First case: A 66 years-old female was diagnosed with primary hyperthyroidism. Her thyroid antibodies were negatives. During the follow-up, she presented a high serum calcium level (2.95 mmol/l) and high Parathormone level (141.3 pg/ml) persisting after the correction of initial low 25-hydroxyvitamin D3. Her PHPT was complicated by osteoporosis and recurrent urolithiasis. Cervical ultrasonography and thyroid scintigraphy affirmed the presence of TMNG and bilateral lower parathyroid adenoma. She underwent a thyroidectomy and parathyroidectomy of the two adenomas. Histopathological examination confirmed the presence of a benign multinodular goiter (MNG) and two parathyroid adenomas. Second case: A 56 years-old female was followed-up for 18 years for MNG. She developed hyperthyroidism (FT4=35 mIU/l) followed by PHPT with hypercalcemia (2.79 mmol/l) and elevated Parathormone level (147 pg/ml) persisting after the correction of initial low 25-hydroxyvitamin D3. Her PHPT was complicated by osteopenia. Cervical ultrasonography and thyroid scintigraphy affirmed the TMNG without finding a parathyroid adenoma.

Conclusion: PHPT associated with thyroid nodules is rare. Hypercalcemia can be found up to a quarter of patients with hyperthyroidism. PHPT should be considered once hypercalcemia persists after correction of the thyroid status and parathyroid hormone should be determined.