Endocrine Abstracts

Background: Primary hyperparathyroidism (PHPT) is caused by a solitary benign adenoma in 80–85% of cases, but may also be due to multi-gland or ectopic disease, hyperplasia, and rarely parathyroid carcinoma. Preoperative localisation studies are important to identify patients suitable for minimally invasive parathyroid surgery. The aim of this study was to evaluate the accuracy of ultrasound (US), parathyroid scintigraphy (MIBI) and computed tomography (CT) utilised in the preoperative setting in a district general hospital, with limited access to single photon-emission computed tomography (SPECT).

Methods: A retrospective study of 88 consecutive patients, who underwent parathyroidectomy for PHPT at a single unit between 2010 and 2014, was conducted. Patients were identified using discharge codes from locally held coding data. The sensitivity and specificity of each imaging modality was compared against histology as the gold standard.

Results: Eithty-two (93%) patients were first presentations of PHPT and six (7%) were relapses, requiring remedial surgery. At surgery, a solitary adenoma was identified in 72 (82%) patients, eight (9%) had parathyroid hyperplasia and one (1%) had parathyroid carcinoma. Preoperatively 100% of patients had US, 82 (93%) MIBI and 67 (59%) CT. Three (3%) had single image modality, 30 (34%) had two and 43 (49%) had three imaging modalities. 43 (53%) parathyroid adenomas were identified with US, 39 (52%) with MIBI and 31 (67%) with CT. Combined US/MIBI were carried out in 82 patients, yielding a sensitivity of 63%. Paired US/CT had a sensitivity of 75% in 52 patients. 21 patients (24%) with inconclusive imaging were referred to tertiary centres for SPECT which successfully identified ten patients. Thirteen patients (15%) underwent neck exploration due to failure of localisation studies. An overall cure rate of 92% was achieved.

Conclusion: Combined US/CT is superior for accurate preoperative localisation of solitary parathyroid adenomas over any single or combination imaging modality.