“Intraoperative parathyroid hormone monitoring in minimally invasive video-assisted parathyroidectomy”

Background. The increasing sensitivity of preoperative localization methods in combination with intraoperative parathyroid hormone (PTHIO) has led to the use of minimally invasive procedures in parathyroid surgery. In addition, it is usually accepted that a decrease in PTHIO values by more than 50% within 5 minutes after excision of hyperfunctioning parathyroid tissue can be considered as a confirmation of the adequacy of the surgical treatment. The aim of this study was to evaluate the impact of use of PTHIO on the success rate of minimally invasive video-assisted parathyroidectomy (MIVAP). Methods. From March 2005 to March 2008 a series of 13 patients with pHPT underwent MIVAP by an anterior approach in combination with preoperative ultrasound and 99Tc-SestaMIBI scintigraphy and PTHIO assay (UniCel® DxI 800 Beckman Coulter, Fullerton, California, U.S.A.). Blood drawings were routinely performed before skin incision (T0), 5 minutes (T1) and 10 minutes (T2) after the excision of the adenomatous tissue. Surgery procedures were concluded when at T1 has been reached a drop in PTHIO level >50% with respect to preoperative levels. PTH, calcemia, complications, pathologic findings, length of hospital stay, operative times, timing and number of sample collection, postoperative pain and cosmetic results, were retrospectively analyzed. Results. 13 patients (10 females, 3 males); median age: 69 years old (range: 33-86); preoperative diagnosis: 12 pts (92%) with sporadic primary hyperparathyroidism (pHPT), one (8%) with pHPT in Multiple Endocrine Neoplasia type 1 (MEN1). In 11 pts (85%) a drop of PTHIO value major than 50% at T1 was observed; for one pts (8%) the drop was of 19.5% (patient in MEN1) while in one pts (8%) a rise of 83.20% was reached. In all but one pts the drop was significant in T2. Only one PTHIO was necessary after 20 minutes after excision (T3). Median operative time and hospitalization was 85 minutes (range: 32-125), and 2 days (range: 2 -5) respectively. In all pts, frozen sections and final histology showed benign disease. Morbidity was 3 (23%) transient hypocalcemias (1 syntomatic) and 1 (8%) haematoma. Conclusions. Our data underline that a PTHIO reduction of more than 50%, five minutes after the resection of adenoma, is a predictor of successful surgery and becomes of fundamental importance in surgical decision making when preoperative imaging studies miss the hyperfunctioning parathyroid tissue. Key-words: intraoperative parathyroid hormone, minimally invasive video-assisted parathyroidectomy, sporadic primitive hyperparathyroidism, 99Tc-sestaMIBI.