Endocrine Abstracts

Introduction: Primary hyperparathyroidism (PHPT) is a common endocrine disorder characterized by hypercalcemia due to an unregulated overproduction of parathyroid hormone (PTH). PHPT is most commonly caused by a single adenoma of the parathyroid gland, usually located just behind the thyroid gland. However, in rare cases, they can have an ectopic location, including intrathyroid adenomas. In some cases, the measurement of intact PTH in the wash out fluid obtained by US-Fine Needle Aspiration (FNA) can be useful in clarifying the etiology of these lesions. Treatment of this condition usually consists of surgical removal of the adenoma.

Case report: A 48-year-old man with complaints of fatigue and malaise was diagnosed with PHPT (total serum calcium concentration, 12.4 mg/dl [reference range, 8.6–10.5 mg/dl]; PTH 462.1 pg/ml [reference range 12–67 pg/ml]) and referred to the Endocrinology department. He presented a background history of symptomatic renal stone disease. A neck ultrasound was performed and the only abnormal finding was a predominantly cystic right lobe thyroid nodule with 21 mm. The patient underwent US-guided FNA of the lesion. PTH measurement in FNA wash-out fluid was significantly elevated (PTH 7199 pg/ml). A week after the procedure he returned to our department reporting he felt neck pain following the procedure and has been noticing distal paraesthesias in the upper limbs. Blood test results showed significant hypocalcemia and supplementation with calcium and calcitriol was started. A 99 Tc-sestamibi scan was performed but did not reveal any abnormalities suggestive of parathyroid disease. An ultrasound reassessment showed a decrease in the thyroid nodule’s size. The patient was closely monitored. Recurrence of hypercalcemia was later observed, nearly a month and a half after FNA. At the date of the last appointment, he was asymptomatic and was offered surgical treatment.

Discussion: We present a case of FNA induced transitory remission of PHPT in a patient with an intrathyroid parathyroid adenoma. We conjecture that intra-nodular hemorrhage might have occurred, which temporarily affected the viability of the autonomous parathyroid tissue. A few similar cases of spontaneous or induced remission of PHPT after FNA had been previously described in the literature. This remission can be transitory or permanent, depending on the degree of cellular damage, thus periodic follow-up of these patients is recommended.