1. Ian Wong Queen Mary Hospital

2. 1849 The glands of Owen – “last major organ to be recognized” J R Soc Med. 2004 October; 97(10): 494–495.

3. + Conventional vs Focused approach + Focused parathyroidectomy + Intraoperative PTH assay + Selective approach + Importance of an experienced surgeon

4. + Conventional - bilateral neck exploration – Identify all parathyroid glands – Excision of all abnormal glands + Focused parathyroidectomy – Primary hyperparathyroidism: 90% adenoma – Preoperative imaging: Sestamibi, Surgeon performed ultrasound (94-99% sensitive in concordant scans) – Intraoperative parathyroid hormone assay (PTH) Endo Prac. Volume 17, Supp 1, March-April 2011 Pg 75-82

5. + Benefits: – Cosmetic – Postoperative pain – Shorter operating time – Ambulatory surgery – Lower risk of recurrent laryngeal nerve injury – Decrease postoperative hypocalcaemia Endo Prac. Volume 17, Supp 1, March-April 2011 Pg 75-82

6. Annals of Surgery Volume 253, Number 3, March 2011 Minimally invasive parathyroidectomy Conventional bilateral neck exploration P-value Cure Rate99.4%97.1%P <0.001 Complication Rate 1.45%3.10%P=0.02

20. + Mechanism, physiology + Protocol + Pitfalls + Other roles + Selective approach to intraoperative PTH J Am Coll Surg. 2009 Sep;209(3):332-43. >50% general surgeons; >90% endocrine surgeons in US adopt intraoperative PTH monitoring

21. + Short half life (3-5min) + Test turn around time: 8-20minutes + Antibodies: sandwich complex technique Endo Prac. Volume 17, Supp 1, March-April 2011. Pg 44-53

22. + Venous access (jugular/peripheral) + Timing (preincisional, preexcision, 5min, 10min +/- 20min) + Interpretation – Miami criteria (>50% PTH drop in 10min) – Charleston criteria (>50% PTH drop and return to normal in 20min) Accuracy (sensitivity 97%, specificity 98%) Decrease false positive from 0.9% to 0.3% Surgery. 2003 Dec;134(6):973-9; discussion 979-81. Endo Prac. Volume 17, Supp 1, March-April 2011. Pg 44-53

23. + Collection site – Jugular veins: higher absolute PTH, longer to reach normal or significant level + Renal Dysfunction: – lesser/slower degree of PTH drop + Laboratory error + Haemolysis + Timing of blood sampling – PTH hormone dynamic Endo Prac. Volume 17, Supp 1, March-April 2011. Pg 44-53

28. + Confirm complete excision + Additional hypersecreting tissue + Differentiating parathyroid from non parathyroid tissues + ?Identifying the side of neck with hypersecreting parathyroid gland (differential jugular venous sampling)

29. + Biochemical fine needle aspiration – Differentiate parathyroid gland – PTH levels in tissue sample – Rapid assay value > 1500 pg/ml – Specificity 100% World J Surg. 2000 Nov;24(11):1319-22.

30. + Differential internal jugular venous sampling – ?10% higher PTH in hypersecreting side in 70-80% – ?Useful in negative or equivocal preoperative localization World J Surg (2010) 34:1299–1303 Group A: Negative sestamibi scan undergoing bilateral neck exploration Group B: Positve Sestamibi scan undergoing focused parathyroidectomy

32. + Add little value in selected group – Changed operative management  74% of imaging discordant group  2% of imaging concordant group + Cost; Operation time + False negative in selected groups – Unnecessary conversions Surgery. 2008 Aug;144(2):299-306.

33. Ann Surg 2010;251: 1122–1126

34. + Intraoperative PTH add little value + Concordant “MIBI” and Ultrasound scan + Intraoperative PTH recommended + Single preoperative localization imaging + Discordant “MIBI” and Ultrasound scan + Reoperative surgery Recommendation Level Ib-III, Grade A/B Langenbecks Arch Surg (2009) 394:799–809

36. 723 (FU >6months) 21 (2.9%) Failed 16(2.3%) Successful localization in subsequent operation 5(0.7%) Intraoperative PTH False Negative 702 (97.1%) Successful

37. 1849 The glands of Owen - last major organ to be recognized” J R Soc Med. 2004 October; 97(10): 494–495.

38. + Focused parathyroidectomy is comparable to (if not superior than) conventional approach + Practitioners need to understand the roles and interpretation of intraoperative PTH + Cost effectiveness of intraoperative PTH in selected groups is debatable + Surgeons’ experience is very important

41. Results Complication rate0.4% Conversion rate3.9 % Overall success rate98.6% IPM sensitivity99.6% IPM accuracy92.9% Operative time (34 vs 60 mins)P<0.001 Ann Surg 2010;251: 1122–1126

42. + Bayes' theorem shows how to determine inverse probabilities: – knowing the conditional probability of B given A, what is the conditional probability of A given B?