Cutoff Point of Intraoperative Parathyroid Hormone in Predicting Successful Parathyroidectomy in Renal Hyperparathyroidism
Sathit Niramitmahapanya MD*, Reshma Chawla MD*, Boontida Vasikasin MD*
Affiliation : * Department of Medicine, Rajavithi Hospital, College of Medicine, Rangsit University, Bangkok, Thailand
Background : It is unclear when intraoperative intact parathyroid hormone (IOPTH) measurement should be performed,
and there is also some uncertainty about the best cutoff point to use in predicting the success of parathyroidectomy in renal
hyperparathyroidism.
Objective : To determine the cutoff values for IOPTH, both for parathyroid levels and for postoperative timing after
parathyroidectomy in order to compare successful parathyroidectomy with persistent hyperparathyroidism in renal
hyperparathyroidism.
Material and Method: This was a retrospective study of 85 patients who underwent total parathyroidectomy with
autotransplantation in the Head and Neck Surgery Department in Rajavithi Hospital between October 1st 2014 and September
30th 2016. IOPTH levels were measured preoperatively at IOPTH 0 minutes, and at 10-minute intervals after successful
parathyroidectomy for a duration of 1 hour (IOPTH at 10, 20, 30, 40, 50 and 60 minutes) with iPTH level on day 3 (72 hours
after surgery) below 65 pg/ml taken as a predictor of successful treatment of renal hyperparathyroidism.
Results : Fifty-eight patients (68.2%) had successful treatment according to the above criteria. The ROC values of the
decrement of IOPTH levels at 10, 20, 30 and 40 minutes were 0.644, 0.767, 0.799, and 0.809 respectively. In all patients that
were successfully treated, the decrement of IOPTH was more than 80%, while all patients whose treatment was unsuccessful
had an IOPTH decrement of less than 70%. An IOPTH level decrement of between 70 and 80% 20 minutes postoperatively
had a sensitivity of 82.1 to 96.4%, while a decrement of IOPTH level of more than 90% after 20 minutes yielded 100%
specificity for successful treatment of renal hyperparathyroidism.
Conclusion : The cutoff point for IOPTH time at 20 minutes with at least a 80% decrement yields a sensitivity of 82.1% for
predicting successful surgery, while more than 90% decrement in IOPTH levels has 100% specificity for predicting successful
treatment.
Keywords : Intraoperative, Intact parathyroid hormone, Hyperparathyroidism and chronic renal failure
