The use of intraoperative parathyroid hormone assay in predicting the success and reduce morbidity of targeted minimal invasive parathyroidectomy for primary hyperparathyroidism.

BACKGROUND: Primary hyperparathyroidism (PHPT) is caused by overproduction of parathyroid hormone (PTH) by a hyperfunctioning parathyroid gland (most commonly a parathyroid adenoma, PTA) or glands. Historically, the most commonly described surgical approach has been bilateral neck exploration (BNE). This study focuses on the outcomes of targeted minimally invasive parathyroidectomy [unilateral neck exploration (UNE), focused exploration (FE)-including endoscope and/or exoscope-assisted parathyroidectomy]. Intraoperative measurement of parathyroid hormone levels (ioPTH) is generally considered confirmation of complete removal of all hyperfunctioning parathyroid tissue. Intraoperative surgical success is evaluated using the modified Miami criteria, with a reported sensitivity of 97%. The aim of this study is to determine the safety FE (targeted/focused procedure), sensitivity, specificity and accuracy of ioPTH measurement, based on samples collected at 5, and 15 minutes after removal of pathological tissue. The study further aims to identify the most appropriate evaluation criteria supported the Miami criteria with the high sensitivity and predictive value supported for surgical success of focused/targeted) parathyroidectomy (morbidity including). Study design is a retrospective analysis of minimally invasive parathyroidectomy (MIPT) procedures indicated for primary PHPT performed between 2020 and 2024.

METHODS: The analyzed cohort included 92 evaluated patients. The analyzed data included preoperative PTH levels, ioPTH levels measured at 5, 10 and 15 minutes and PTH levels on the third postoperative day. The analyze used statistic: sensitivity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were evaluated for the various ioPTH criteria. Confidence intervals were calculated using a confusion matrix. We used the Chi-squared test, F-test to compare the time-intervals and box graphs used for presentation. We used the MedCalc software.

RESULTS: For data analysis, six criteria for evaluating the intraoperative decline in PTH levels were defined. The criterion with the high sensitivity (99%) was assessment of PTH levels 10 minutes after resection of the PTA, combined with evaluation of the decrease in PTH levels between 5 and 15 minutes after resection.

CONCLUSIONS: The focused (targeted) lateral (back door) approach parathyroidectomy is the safe and effective therapy of primary PHPT based on the results of very low incidence of RLN palsy (0.0%) in presented cohort. We would like present an additional sensitive criterium for assessment of the procedure function effect supporting Miami criteria's using ioPTH measurement: (I) 0-10: a ≥50% decrease in PTH or a decrease to within the normal range; (II) 5-15: a ≥50% decrease in PTH or a decrease to within the normal range. This both parameters predict surgical success with a sensitivity of 98.8% and a low false-negative (FN) rate of 1.1%. The PPV was 0.88. Both used intervals eliminated the influence of the spike effect on the prediction of treatment success.