Intact Parathyroid Hormone (iPTH) as a Predictor of Symptomatic Hypocalcemia after Total Thyroidectomy; A Cross Sectional Study

Abstract

Background: This study aimed to measure levels of intact parathyroid hormone (iPTH) following total or
completion thyroidectomy, to evaluate its role in diagnosing symptomatic hypocalcemia in affected patients.
Methods: This cross-sectional study was conducted on patients who underwent total or completion thyroidectomy
during 2014–2015. Serum iPTH and calcium levels were measured immediately after surgical wound closure.
Hypocalcemia symptoms were assessed every 8 hours postoperatively. The relationship between serum calcium
and iPTH levels was analyzed. Statistical tests included repeated measures ANOVA, t-test, Chi-square, Mann–
Whitney U, and ANOVA. The optimal iPTH cut-off value was determined using receiver operating characteristic
(ROC) curve analysis.
Results: Of 112 surgical patients, iPTH was measured in 100 cases. Twenty patients developed symptomatic
hypocalcemia. There were no statistically significant differences among normocalcemic, asymptomatic
hypocalcemic, and symptomatic hypocalcemic groups in terms of age, preoperative calcium levels, or length of
hospitalization (P = 0.48, P = 0.46, and P = 0.6, respectively). iPTH levels differed across the groups, notably
between asymptomatic and symptomatic hypocalcemic patients (P = 0.029). ROC analysis identified an optimal
iPTH cut-off value of 18.9 pg/mL, with sensitivity and specificity of 90% and 56.52%, respectively.
Conclusions: iPTH measurement immediately following thyroidectomy shows utility in predicting symptomatic
hypocalcemia and may play an important role in identifying patients at risk postoperatively.