title: Intraoperative parathyroid hormone assay: an accurate predictor of symptomatic hypocalcemia following thyroidectomy.
abstract: OBJECTIVE
  Intraoperative parathyroid hormone (IOPTH) assay is useful for predicting symptomatic hypocalcemia following total thyroidectomy.
  
  
  METHODS
  A prospective study of 30 patients undergoing total thyroidectomy with IOPTH levels obtained following skin closure and ionized calcium (Ca2+) levels obtained 6 hours postoperatively and on postoperative day 1. All patients were evaluated for symptoms of hypocalcemia.
  
  
  METHODS
  University teaching hospital.
  
  
  METHODS
  Patients who developed symptomatic hypocalcemia were compared with asymptomatic patients in regard to age, diagnosis, thyroid weight, thyrotropin level, Ca2+ level, parathyroid status, and IOPTH level.
  
  
  RESULTS
  The onset of symptomatic hypocalcemia ranged from 8 to 48 hours postoperatively (n = 10). One patient required readmission. Of 10 patients with symptoms, 5 developed tetany. There were no significant differences in age, diagnosis, thyroid weight, thyrotropin level, or the number of parathyroid glands preserved in patients with or without symptomatic hypocalcemia. All patients with an IOPTH level of less than 10 pg/mL (1.1 pmol/L) had symptoms (n = 8). The mean +/- SD IOPTH level (7.6 +/- 12.0 pg/mL [0.8 +/- 1.3 pmol/L]) in patients who developed symptomatic hypocalcemia was significantly lower than the mean IOPTH level (55.7 +/- 31.8 pg/mL [5.9 +/- 3.3 pmol/L]) in patients without symptoms (P =.001). The 6-hour and postoperative day 1 Ca2+ levels were significantly lower in patients with symptomatic hypocalcemia (P =.19 and P =.13, respectively). An IOPTH level of less than 10 pg/mL is 80% sensitive and 100% specific for the development of symptomatic hypocalcemia.
  
  
  CONCLUSIONS
  The incorporation of the IOPTH assay in the management of thyroid disease is recommended to prevent and prospectively treat symptomatic hypocalcemia, thereby reducing readmissions following thyroidectomy.
authors.affiliation: Department of Surgery, University of Texas Health Science Center at San Antonio, 78284, USA. richardsm@uthsca.edu
authors.forename: Melanie L
authors.initials: ML
authors.lastname: Richards
authors.forename: Juliane
authors.initials: J
authors.lastname: Bingener-Casey
authors.forename: Damon
authors.initials: D
authors.lastname: Pierce
authors.forename: William E
authors.initials: WE
authors.lastname: Strodel
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Sirinek
mesh_terms: D000328:Adult; D002118:Calcium / Q000097:blood; D005260:Female; D006801:Humans; D006996:Hypocalcemia / Q000097:blood / Q000209:etiology*; D007118:Immunoassay; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D010281:Parathyroid Hormone / Q000097:blood*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D013965:Thyroidectomy / Q000009:adverse effects*
chemical_list: D010281:Parathyroid Hormone; D002118:Calcium