title: A prospective evaluation of quick intraoperative parathyroid hormone assay at the time of skin closure in predicting clinically relevant hypocalcemia after thyroidectomy.
abstract: BACKGROUND
  Post-thyroidectomy hypocalcemia is a major contributing factor in delayed hospital discharge and dissuading surgeons from ambulatory thyroidectomy. We prospectively evaluated the accuracy and reliability of quick parathyroid hormone level measurement at skin closure (PTH-SC) in predicting clinically relevant hypocalcemia (i.e., patients requiring calcium ± calcitriol supplements on hospital discharge).
  
  
  METHODS
  Of the 117 patients who underwent a total or completion total thyroidectomy and PTH-SC, 17 (14.5 %) had hypocalcemic symptoms or adjusted calcium <1.90 mmol/L requiring calcium and/or calcitriol supplements on discharge. Serum calcium was checked regularly in the perioperative period until stabilization and an additional quick PTH was checked on the following morning (PTH-D1). Univariate and multivariate analyses were performed to evaluate potential preoperative clinicopathologic factors and postoperative day 0 biochemical indicators. Youden's index and the area under the ROC curve (AUC) were used to determine the best cutoff value and predictability of significant variables or criteria, respectively.
  
  
  RESULTS
  In the multivariate analysis, low preoperative adjusted calcium (p = 0.041) and low PTH-SC (p = 0.001) were the two independent variables associated with hypocalcemia. PTH-SC (≤1 or >1 pmol/L) had a higher specificity (95.0 %) and AUC (0.887) than serial calcium monitoring or PTH-D1 alone. Although 3/98 of patients with PTH-SC >1 pmol/L required calcium supplements on discharge, they required only the minimum amount to maintain normocalcemia.
  
  
  CONCLUSIONS
  PTH-SC is an accurate and reliable means of predicting clinically relevant hypocalcemia. It would be reasonable to discharge those with PTH-SC >1 pmol/L on the same operative day as the risk of life-threatening hypocalcemia would seem unlikely.
authors.affiliation: Division of Endocrine Surgery, Department of Surgery, University of Hong Kong, Pokfulam, Hong Kong SAR, China. blang@hkucc.hku.hk
authors.forename: Brian Hung-Hin
authors.initials: BH
authors.lastname: Lang
authors.forename: Patricia Chun-Ling
authors.initials: PC
authors.lastname: Yih
authors.forename: Ka Kin
authors.initials: KK
authors.lastname: Ng
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D003661:Decision Support Techniques; D005260:Female; D006801:Humans; D006996:Hypocalcemia / Q000097:blood / Q000175:diagnosis* / Q000209:etiology; D007430:Intraoperative Care; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010281:Parathyroid Hormone / Q000097:blood*; D011183:Postoperative Complications / Q000175:diagnosis* / Q000209:etiology; D011446:Prospective Studies; D012372:ROC Curve; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity; D013959:Thyroid Diseases / Q000601:surgery*; D013965:Thyroidectomy; D055815:Young Adult
chemical_list: D015415:Biomarkers; D010281:Parathyroid Hormone