Endocrine Abstracts

Introduction: Primary hyperparathyroidism is the most common cause of hypercalcemia in the outpatient setting, and a single parathyroid adenoma is usually the culprit. Clinical presentation is commonly dictated by hypercalcemia. Symptoms can range from mild non-specific malaise and gastrointestinal disturbances, through bone disease, kidney stones, cardiovascular and neuromuscular dysfunction to, ultimately, coma and death. However, the vast majority of patients are asymptomatic.

Case report: A 46-year-old female with a half-year endocrinology monitoring for type 2 diabetes and obesity, resorted to our hospital after 3 weeks’ evolution of persistent nausea and vomiting. Laboratory workup showed increased PTH levels (596 pg/ml), severe hypercalcemia (17.4 mg/dl), mild hypophosphatemia (2.4 mg/dl), acute kidney injury (creatinine clearance 34 ml/min) and hyperuricemia (14.8 mg/dl). A 25-hydroxyvitamin D deficiency was also present (6.5 ng/ml). The first neck ultrasound did not show abnormalities; 99mTc-sestaMIBI scan was negative. Repetition of neck ultrasound revealed a left-postero-inferior nodule likely to correspond to an enlarged parathyroid. The cytological evaluation supported this hypothesis. Pamidronate, antiemetics and volume expansion with isotonic saline reverted the clinico-laboratory condition and served as a bridge to parathyroidectomy. Surgery went uneventful and a 3 cm inferior-left parathyroid was sent to anatomopathological examination. The final diagnosis was parathyroid adenoma. In subsequent postoperative follow-up the patient was asymptomatic and had normal serum calcium levels (9.3 mg/dl) and slightly upper-limit PTH (77.3 pg/ml).

Conclusion: Despite the considerable size of the resected parathyroid, initial ultrasound failed to locate it. Seeking for a topographical diagnosis, a second ultrasound was performed by a different operator in our hospital. This case highlights the importance of carefully selecting experienced centers to address parathyroid preoperative studies. Furthermore, despite the adenoma size, its inferior location, and the associated severe hypercalcemia, the 99mTc-sestaMIBI scan was negative, reminding of potential false-negative results of this method.