Endocrine Abstracts

Introduction: Commonly used pre-operative methods (ultrasonography and sestamibi scan) to localize the culprit parathyroid gland(s) in patients with primary hyperparathyroidism (PHPT), frequently yield false positive or false negative results. Parathyroid hormone (PTH) washout after fine-needle aspiration (FNA) may allow for a targeted surgical approach. The aim of this study was to test the diagnostic value of preoperative PTH washout after FNA in PHPT patients.

Methods/design: Retrospective study conducted in a tertiary centre. Ultrasound-guided FNA was performed if a structure compatible with a parathyroid adenoma was found on cervical ultrasound. A PTH washout cut-off value was considered diagnostic if it was higher than the concomitant serum PTH value.

Results: Twenty-nine patients (2 (6.8%) males, mean age 58.6±9.1 years) were included. Mean pre-operative serum PTH levels were 194.2±176.8 pg/ml (normal: 10–53), while serum calcium and 25-hydroxy-vitamin D levels were 11.5±1.4 mg/dl (normal: 8.8–10.6) and 24.1±20.5 ng/ml (deficiency: <20 ng/ml) respectively. Post-operative serum PTH and calcium levels were 45.9±26.3 pg/ml and 9.04±0.7 mg/dl respectively. A single adenoma was identified in 26 (89.7%) patients and a double adenoma in 1 (3.4%). Two (6.9%) patients were harbouring an ectopic parathyroid adenoma (upper mediastinal and intrathyroid). Twenty-four patients (82.7%) had elevated PTH washout concentrations (mean values: 2009.5±1417.6 pg/ml). True positive and false negative results were 24 and 4 respectively. The sensitivity, specificity and positive predictive value (PPV) were 85.71, 100, and 100% respectively. Interestingly, in ten out of 12 patients with a negative sestamibi scan, the PTH washout yielded a truly positive result.

Conclusions: Elevated PTH washout concentrations after ultrasound-guided FNA is an highly accurate diagnostic tool in identifying parathyroid adenomas and guiding parathyroid surgery.