Authors’ Reply: A Review of Parathyroid Surgery for Primary Hyperparathyroidism from the United Kingdom Registry of Endocrine and Thyroid Surgery

Abstract

Dear Dr Idrees and Associate Professor Maylivaganan, Thank you for taking interest in our recent work [1] and your ‘‘Letter to the editor’’. In response to your first question of ‘‘can we reliably record the efficiency only with postoperative serum calcium as a marker of biochemical cure without a post-operative serum PTH level?’’, we, the authors, stated clearly in our discussion that we acknowledged the limitations of the United Kingdom Registry of Endocrine and Thyroid Surgeons (UKRETS), as such it was not possible to report on the true ‘‘cure’’ rate, as defined by the American Association of Endocrine Surgeons (AAES). The AAES define ‘‘cure’’ as the ‘‘re-establishment of normal calcium homeostasis lasting a minimum of 6 months post-operatively’’[2]. Thus, we settled for the term ‘‘post-operative normocalcaemia’’ instead, to allow this differentiation. In terms of the measurement of postoperative serum PTH levels, the AAES state that there is no role for the routine measurement of serum PTH in the immediate post-operative period in the normocalcaemic patient [2]. The authors do acknowledge that in cases of normocalcaemic primary hyperparathyroidism (ncPHPT), the definition of ‘‘cure’’ is the normalisation of calcium and PTH more than 6 months after surgery, as stated by the AAES [2], but it was not possible from the UKRETS to differentiate the ncPHPT patients from PHPT patients to allow this analysis. Also, as mentioned in our work, the UKRETS, at the time of analysis, did not collect data on long-term (more than 6 months) follow-up data. With regards to the inclusion of the analysis of surgical adjuncts in our work, we did feel that the inclusion of the analysis of intra-operative PTH (ioPTH) was important. The UKRETS does allows surgeons to record the use of surgical adjuncts, in the form of methylene blue (MB), intra-operative gamma probe and ioPTH. The authors did not include the analysis of MB or the gamma probe, as we found that the use of MB had dramatically fallen from 2004 to 2017 and the use of the gamma probe was consistently low (always\\ 4%). However, we did find that the use of ioPTH has shown a consistent rise across the years, as mentioned in our work. This was accompanied by the rise in the number of targeted parathyroidectomies (tPTx) carried out throughout this time. The AAES state that ioPTH is recommended in image guided, focused parathyroidectomy to avoid higher failure rates [2]. Due to these factors, we felt it important to include the analysis of intra-operative adjuncts in our work. From our data, there is no obvious suggestion that there is a rise in the proportion of bilateral neck explorations (BNEs) taking place, where all four parathyroid glands are being sought out. Finally, with regards to outcome differences between trainees and consultants, we did not feel this a major point of interest to analyse. This is because according to the Fifth National Audit Report 2017 [3], the vast majority of all first-time parathyroid operations (9728/11557, 84.2%) were carried out by consultants, and these figures would be similar for all first-time PHPT operations and any differing outcomes (trainees vs consultants) may be skewed due to & Hiro Ishii [email protected]