title: Post-thyroidectomy hypocalcemia is related to parathyroid dysfunction even in patients with normal parathyroid hormone concentrations early after surgery.
abstract: BACKGROUND
  Hypocalcemia may develop even in the presence of normal postoperative parathyroid hormone (PTH) concentrations. We aimed to identify risk factors of hypocalcemia in patients with normal PTH concentration early after total thyroidectomy (TT).
  
  
  METHODS
  We included 1,504 consecutive patients who underwent TT between January 2012 and December 2013. Significant hypocalcemia was defined as serum calcium concentrations of <8.0 mg/dL.
  
  
  RESULTS
  Overall, 333 patients had subnormal PTH 4 hours after surgery (4-hour PTH; <10 pg/mL) and received oral calcium (OC) and calcitriol supplementation. Among the 1,171 patients with normal 4-hour PTH (≥ 10 pg/mL; euparathyroid), 211 experienced hypocalcemia and required OC administration. Among the euparathyroid patients, no difference was found between normocalcemic and hypocalcemic patients in terms of age, hormonal status, preoperative PTH, 25-hydroxy vitamin D (25OH-VD), magnesium, and phosphate concentrations. On univariate analysis, euparathyroid hypocalcemic patients were more frequently females, had significantly lower preoperative serum calcium and 4-hour PTH concentrations, and greater decreases in PTH. Independent risk factors for hypocalcemia with normal 4-hour PTH were preoperative serum calcium concentration and PTH decline of ≥ 50%.
  
  
  CONCLUSIONS
  Female sex, toxic goiter, and 25OH-VD deficiency are not risk factors for post-TT hypocalcemia. Relative parathyroid insufficiency seems to be the principal mechanism of post-thyroidectomy hypocalcemia, even in patients with normal postoperative PTH concentrations.
authors.affiliation: U.O. Chirurgia Endocrina e Metabolica, Policlinico "A. Gemelli", Università Cattolica del Sacro Cuore, Rome, Italy. Electronic address: marcoraffaelli@rm.unicatt.it.
authors.forename: Marco
authors.initials: M
authors.lastname: Raffaelli
authors.affiliation: U.O. Chirurgia Endocrina e Metabolica, Policlinico "A. Gemelli", Università Cattolica del Sacro Cuore, Rome, Italy.
authors.forename: Carmela
authors.initials: C
authors.lastname: De Crea
authors.affiliation: U.O. Chirurgia Endocrina e Metabolica, Policlinico "A. Gemelli", Università Cattolica del Sacro Cuore, Rome, Italy.
authors.forename: Gerardo
authors.initials: G
authors.lastname: D'Amato
authors.affiliation: U.O. Igiene Ospedaliera, Policlinico "A. Gemelli", Università Cattolica del Sacro Cuore, Rome, Italy.
authors.forename: Umberto
authors.initials: U
authors.lastname: Moscato
authors.affiliation: U.O. Chirurgia Endocrina e Metabolica, Policlinico "A. Gemelli", Università Cattolica del Sacro Cuore, Rome, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Bellantone
authors.affiliation: U.O. Analisi Ormonali e Biologia Molecolare Clinica, Policlinico "A. Gemelli", Università Cattolica del Sacro Cuore, Rome, Italy.
authors.forename: Cinzia
authors.initials: C
authors.lastname: Carrozza
authors.affiliation: U.O. Chirurgia Endocrina e Metabolica, Policlinico "A. Gemelli", Università Cattolica del Sacro Cuore, Rome, Italy.
authors.forename: Celestino Pio
authors.initials: CP
authors.lastname: Lombardi
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 / Q000209:etiology*; D007011:Hypoparathyroidism / Q000097:blood* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood*; D011446:Prospective Studies; D012307:Risk Factors; D013965:Thyroidectomy / Q000009:adverse effects*; D013997:Time Factors; D055815:Young Adult
chemical_list: D010281:Parathyroid Hormone; D002118:Calcium