title: Transient and permanent hypocalcemia after total thyroidectomy: Early predictive factors and long-term follow-up results.
abstract: BACKGROUND
  Post-thyroidectomy hypocalcemia is among the most common complications of total thyroidectomy. The purpose of this study was to evaluate early predictive factors and long-term changes in intact parathyroid hormone (iPTH) levels in patients with transient and permanent hypocalcemia after total thyroidectomy.
  
  
  METHODS
  A total of 349 consecutive patients who underwent total thyroidectomy with or without neck dissection between 2009 and 2011 were reviewed. PTH, total calcium (Ca), and ionized Ca (iCa) levels were evaluated at 1 hour, and 1, 3, 5, and 7 days, and 1, 3, 6, and 12 months postoperatively. Biochemical profiles at 1 hour after total thyroidectomy in patients with transient and permanent hypocalcemia were compared. Patients with postoperative hypocalcemia were followed for 12 months.
  
  
  RESULTS
  Lesser preoperative serum levels of Ca and more extensive surgery were significantly associated with postoperative hypocalcemia (P < .05). The absolute level and relative decline (%) in iPTH at 1 hour were the most reliable predictors of postoperative hypocalcemia according to the receiver operating characteristics curve, with a threshold of 10.42 pg/mL and 70%. Sensitivity and specificity of the predictors were 83.4% (95% CI, 76.4-89.1), 100% (95% CI, 84.6-100.0), 84.1 (95% CI, 77.2-89.7), and 95.5% (95% CI, 77.2-99.9), respectively. Parathyroid function recovered in the first month after total thyroidectomy in 78 of 99 patients (79%) with transient hypocalcemia. However, 46 of 61 patients (74%) with a subnormal iPTH level at 3 months after surgery had permanent hypocalcemia.
  
  
  CONCLUSIONS
  Mean postoperative PTH level and the mean relative decline in PTH measured 1 hour postoperatively were the most reliable predictors of postoperative or permanent hypocalcemia.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Cancer Research Institute, Research Institute for Medical Sciences, Chungnam National University College of Medicine, Daejeon, Korea.
authors.forename: Sung Tae
authors.initials: ST
authors.lastname: Seo
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Cancer Research Institute, Research Institute for Medical Sciences, Chungnam National University College of Medicine, Daejeon, Korea.
authors.forename: Jae Won
authors.initials: JW
authors.lastname: Chang
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Yanbian University Hospital, Jilin Yanji, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Jin
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, Research Institute of Medical Science, Konkuk University School of Medicine, Seoul, the Republic of Korea.
authors.forename: Young Chang
authors.initials: YC
authors.lastname: Lim
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Cancer Research Institute, Research Institute for Medical Sciences, Chungnam National University College of Medicine, Daejeon, Korea.
authors.forename: Ki-Sang
authors.initials: KS
authors.lastname: Rha
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Cancer Research Institute, Research Institute for Medical Sciences, Chungnam National University College of Medicine, Daejeon, Korea. Electronic address: bskoo515@cnuh.co.kr.
authors.forename: Bon Seok
authors.initials: BS
authors.lastname: Koo
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D002118:Calcium / Q000097:blood*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006996:Hypocalcemia / Q000097:blood* / Q000145:classification / Q000453:epidemiology*; D015994:Incidence; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood*; D011184:Postoperative Period; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012307:Risk Factors; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D013965:Thyroidectomy / Q000009:adverse effects*; D013997:Time Factors
chemical_list: D015415:Biomarkers; D010281:Parathyroid Hormone; D002118:Calcium