Ian WongQueen Mary Hospital

1849The glands of Owen – “last major organ to be

recognized”

J R Soc Med. 2004 October; 97(10): 494–495.

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

+ 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

+ 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

Annals of Surgery Volume 253, Number 3, March 2011

Minimally invasive parathyroidectomy

Conventional bilateral neck exploration

P-value

Cure Rate 99.4% 97.1% P <0.001

Complication Rate

1.45% 3.10% P=0.02

+ 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

+ 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

+ 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

+ 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

Endo Prac. Volume 17, Supp 1 , March-April 2011. Pg 44-53

Endo Prac. Volume 17, Supp 1 , March-April 2011. Pg 44-53

Endo Prac. Volume 17, Supp 1 , March-April 2011. Pg 44-53

Endo Prac. Volume 17, Supp 1 , March-April 2011. Pg 44-53

+ 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)

+ 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.

+ 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

+ 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.

Ann Surg 2010;251: 1122–1126

+ 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/BLangenbecks Arch Surg (2009) 394:799–809

1849The glands of Owen - last major organ to be

recognized”

J R Soc Med. 2004 October; 97(10): 494–495.

+ 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

Results

Complication rate 0.4%

Conversion rate 3.9 %

Overall success rate 98.6%

IPM sensitivity 99.6%

IPM accuracy 92.9%

Operative time (34 vs 60 mins) P<0.001

Ann Surg 2010;251: 1122–1126

+ 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?