In primary hyperparathyroidism(pHPT), suppression over other glands due to autonomy of pathological gland is frequently observed. In this study, we aimed to evaluate contribution of suppression of remaining parathyroid glands in pHPT for predicting surgical cure.

202 pHPT patients who underwent focused surgery or unilateral exploration were included. Patients were divided into 2 groups; patients with suppression at 6th hour(group1)(PTH<15ng/L) and without suppression(group2). Hypercalcemia continuing till 6 months was defined as persistent disease(pPHPT); achieving normocalcemia at 6 months was defined as cure. Group1 and 2 were compared regarding preoperative and early postoperative biochemical findings, imaging features, and pPHPT development. Significant features obtained from univariate analysis were evaluated using multivariate analysis for pPHPT.

The rate of pPHPT was detected significantly higher in group2 compared to group1 (18 of 78 (23.1%), 7 of 124 (5.6%);p<0.001)(OR:5.014(95%CI:1.985-12.669)). Only PTH suppression was determined as a significant independent risk factor in predicting cure(OR:0.191(95%CI:0.072-0.507,p=0.001)). PTH value below 17.8 ng/L at postoperative 6th hour could predict cure with 72.9% sensitivity, 72% specificity.

Early postoperative PTH supression is highly associated with cure. The rate of pPHPT is significantly higher in non-supressed group. Although hypercalcemia can cause PTH suppression over both sleeping pathological glands and normal glands, its suppression over the remnant sleeping parathyroid glands is less significant. Thus, in follow-up strategies, it should be considered that the possibility of potential pathological sleeping parathyroid tumor leading to pPHPT is high in patients without early PTH suppression.