Endocrine Abstracts (2019) 65 P137 | DOI: 10.1530/endoabs.65.P137

Long term outcomes following parathyroidectomy in patients with multiple endocrine neoplasia type 1: A retrospective cohort study

Ultan Healy1, Katie English1, Hannah Elizabeth Bacon1, Ashley B Grossman1, Brian Shine1, Rajesh V Thakker2, Christine JH May1, Aparna Pal1, Radu Mihai3 & Bahram Jafar-Mohammadi1

1Oxford Centre for Diabetes, Endocrinology and Metabolism, Oxford University Hospitals NHS Foundation Trust, Oxford, UK; 2Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK; 3Department of Endocrine Surgery, Churchill Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK

Primary hyperparathyroidism (PHP), usually due to multigland hyperplasia, occurs in >90% of patients with multiple endocrine neoplasia type 1 (MEN1). The literature is divided on the optimal surgical management for such patients. We report a retrospective cohort study on the long-term outcomes associated with limited, subtotal, or total parathyroidectomy as initial surgery for PHP in MEN1. The primary endpoint was recurrent PHP defined as an adjusted serum calcium >2.6 mmol/l with elevated or normal serum PTH. Kaplan–Meier curves were constructed for the primary endpoint. Rates of permanent post-surgical hypoparathyroidism (PPSH) were observed, and between group differences were assessed using Fisher’s exact test. 51 MEN1 subjects, with median post-surgical follow-up of 11.8 years (IQR 7.2–17.6), were included and divided into 3 groups based on the number of glands removed at initial surgery; limited (<3 glands, n=26), subtotal (3/3.5 glands, n=16), and total (4 glands, n=9). The proportions of patients with recurrent PHP at last follow-up were 17/26 (65.4%), 11/16 (68.8%) and 3/9 (33.3%) respectively. Median (95% CI) recurrence-free survival was 4.6 (1.0–6.8), 9.8 (2.5–30.4) and 30.5 (2.0-undefined) years, respectively. Compared to limited parathyroidectomy, both total and subtotal parathyroidectomy were associated with longer recurrence-free survival (P=0.001 and P=0.016, respectively), with no difference seen between total and subtotal parathyroidectomy (P=0.4). Rates of PPSH were higher in the total parathyroidectomy group (5/9, 55.6%) compared to both limited (2/26, 7.7%, P=0.006) and subtotal groups (1/16, 6.3%, P=0.012). We conclude that, compared to both total and subtotal parathyroidectomy, limited parathyroidectomy is associated with a greater likelihood of recurrent PHP. Conversely, compared to both limited and subtotal parathyroidectomy, total parathyroidectomy is associated with higher rates of PPSH. Based on our data, subtotal parathyroidectomy may thus be the optimal strategy to balance these outcomes.