title: Evolution of blood magnesium and phosphorus ion levels following thyroidectomy and correlation with total calcium values.
abstract: OBJECTIVE
  magnesium ion concentration is directly related and phosphorus ion concentration is inversely related to calcemia. The aim of this study was to evaluate the evolution of magnesium and phosphorus ion levels in patients undergoing thyroidectomy and correlate these with changes to calcium concentration.
  
  
  METHODS
  prospective study at the Alpha Institute of Gastroenterology, Hospital das Clínicas, Universidade Federal de Minas Gerais.
  
  
  METHODS
  the study included 333 patients, of both genders and mean age 45 ± 15 years, who underwent thyroidectomy between 2000 and 2005. Total calcium, phosphorus and magnesium were measured in the blood preoperatively and 24 and 48 hours postoperatively. Ionic changes were evaluated according to the presence or absence of postoperative hypocalcemia.
  
  
  RESULTS
  there were statistically significant drops in blood phosphorus levels 24 and 48 hours after thyroidectomy, compared with preoperative values, in the patients without hypocalcemia. In the patients who developed hypocalcemia, there was a significant drop in plasma phosphorus on the first postoperative day and an increase (also statistically significant) on the second day, in relation to preoperative phosphorus levels. A significant drop in postoperative magnesium was also observed on the first and second days after thyroidectomy in the patients with hypocalcemia, in relation to preoperative levels. In the patients without hypocalcemia, the drop in magnesium was significant on the first day, but there was no difference on the second day.
  
  
  CONCLUSIONS
  despite the postoperative changes, neither magnesium nor phosphorus ion levels had any role in post-thyroidectomy calcemia.
authors.affiliation: Instituto Alfa de Gastroenterologia, Hospital das Clínicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil. avras@bol.com.br
authors.forename: Alexandre de Andrade
authors.initials: Ade A
authors.lastname: Sousa
authors.forename: José Maria Porcaro
authors.initials: JM
authors.lastname: Salles
authors.forename: João Marcos Arantes
authors.initials: JM
authors.lastname: Soares
authors.forename: Gustavo Meyer de
authors.initials: GM
authors.lastname: Moraes
authors.forename: Jomar Rezende
authors.initials: JR
authors.lastname: Carvalho
authors.forename: Paulo Roberto
authors.initials: PR
authors.lastname: Savassi-Rocha
mesh_terms: D002118:Calcium / Q000097:blood*; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006996:Hypocalcemia / Q000097:blood* / Q000209:etiology; D008274:Magnesium / Q000097:blood*; D008297:Male; D008875:Middle Aged; D010758:Phosphorus / Q000097:blood*; D011184:Postoperative Period; D011300:Preoperative Care; D011446:Prospective Studies; D013965:Thyroidectomy / Q000009:adverse effects*
chemical_list: D010758:Phosphorus; D008274:Magnesium; D002118:Calcium