title: [Role of parathyroid hormone measurement in prediction for symptomatic hypocalcaemia after total thyroidectomy].
abstract: OBJECTIVE
  To evaluate the role of parathyroid hormone (PTH) and serum calcium in prediction for hypocalcaemia after total thyroidectomy.
  
  
  METHODS
  One hundred and sixty-five patients undergoing total or complete total thyroidectomy were reviewed retrospectively. The indications included bilateral carcinoma, undifferential carcinoma, surroundings invasion, distant metastasis and huge benign lesions. Preoperative and postoperative PTH, calcium concentrations and their decline levels were compared between Jan. 2005 and May 2009. The role of PTH value and decline level predicting for symptomatic hypocalcaemia were analyzed by receiver operator characteristics (ROC) curve.
  
  
  RESULTS
  After total thyroidectomy, 85 patients (51.5%) developed hypocalcemia. Symptoms were reported by 36 patients (21.8%). The mean concentration of PTH for normocalcaemia (80 cases), asymptomatic hypocalcaemia (49 cases) and symptomatic patients (36 cases) were 31.0 ng/L, 19.6 ng/L and 11.9 ng/L, respectively. The mean decline level for the three groups were 28.6%, 52.6% and 78.0%, respectively. PTH value and its decline level had a poor predicting value for symptomatic hypocalcaemia and high negative predicting value for asymptomatic patients. The serum calcium concentration more than 2.0 mmol/L, PTH level higher than 15 ng/L and PTH decline less than 50% had the good negative predicting value of 97.6%, 90.3% and 96.5%, respectively.
  
  
  CONCLUSIONS
  Postoperative PTH and its decline level were significantly correlated with postoperative serum calcium concentration but had a low accuracy for predicting symptomatic hypocalcaemia. The serum calcium concentration more than 2.0 mmol/L, PTH level higher than 15 ng/L and PTH decline less than 50% had the good predicting value for asymptomatic patients. Calcium should be routinely supplemented in the first 24 h after total thyroidectomy to reduce the rate of hypocalcemia and the severity of hypocalcemia symptoms.
authors.affiliation: Department of Head and Neck Surgery of Cancer Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing 100021, China.
authors.forename: Chang-ming
authors.initials: CM
authors.lastname: An
authors.forename: Ping-zhang
authors.initials: PZ
authors.lastname: Tang
authors.forename: Zhen-gang
authors.initials: ZG
authors.lastname: Xu
authors.forename: Bin
authors.initials: B
authors.lastname: Zhang
authors.forename: Zong-min
authors.initials: ZM
authors.lastname: Zhang
authors.forename: Dan-gui
authors.initials: DG
authors.lastname: Yan
authors.forename: Zheng-jiang
authors.initials: ZJ
authors.lastname: Li
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002118:Calcium / Q000097:blood*; D002648:Child; D005260:Female; D006801:Humans; D006996:Hypocalcemia / Q000097:blood / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000032:analysis*; D011184:Postoperative Period; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000601:surgery; D013965:Thyroidectomy / Q000009:adverse effects*; D055815:Young Adult
chemical_list: D010281:Parathyroid Hormone; D002118:Calcium