title: Secretory capacity of the parathyroid glands after total thyroidectomy in normocalcemic subjects.
abstract: BACKGROUND
  Hypocalcemia, transient or permanent, represents a common complication after total thyroidectomy, but data on the secretory capacity of the parathyroid glands in thyroidectomized patients without clinical or biochemical hypocalcemia are limited.
  
  
  METHODS
  To address this issue, we studied the parathyroid response to acute hypocalcemia induced by iv infusion of sodium bicarbonate in normocalcemic patients submitted to total thyroidectomy at the early postoperative period and 3 months later.
  
  
  METHODS
  Sixty patients who underwent total thyroidectomy for benign thyroid disease and did not develop clinical or biochemical hypocalcemia and hypoparathyroidism postoperatively and 50 healthy volunteers were included in the study. Patients (at 48 h and 3 months after surgery) and controls (after overnight fast) were subjected to a sodium bicarbonate infusion test.
  
  
  RESULTS
  In healthy volunteers plasma intact PTH increased significantly at 3 min after infusion (4.42 ± 0.15 ng/ml vs. 11.22 ± 0.5 ng/ml, P < 0.001) and gradually returned to baseline values. In the thyroidectomized patients, mean PTH levels were also increased after sodium bicarbonate infusion but to a significantly lesser degree compared with healthy controls (1.77 mean fold increase vs. 2.57 mean fold increase, respectively, P < 0.001). Using as criterion the lowest fold increase of plasma PTH levels at 3 min after infusion observed in healthy volunteers, 38% of the thyroidectomized patients at 48 h after surgery and 6.6% of the patients at 3 months after surgery demonstrated a diminished PTH response to acute hypocalcemia induced by sodium bicarbonate infusion.
  
  
  CONCLUSIONS
  In thyroidectomized patients, normal postoperative calcium and PTH values do not exclude a reduced secretory response of the parathyroids to hypocalcemic stimuli.
authors.affiliation: Department of Endocrinology and Metabolism, Aristotle University of Thessaloniki, AHEPA University Hospital, 1 Stilponos Kyriakidi Street, 54636 Thessaloniki, Greece.
authors.forename: Olympia E
authors.initials: OE
authors.lastname: Anastasiou
authors.forename: Maria P
authors.initials: MP
authors.lastname: Yavropoulou
authors.forename: Theodosis S
authors.initials: TS
authors.lastname: Papavramidis
authors.forename: Chrysoula
authors.initials: C
authors.lastname: Tzouvara
authors.forename: Konstantina
authors.initials: K
authors.lastname: Triantafyllopoulou
authors.forename: Spiros
authors.initials: S
authors.lastname: Papavramidis
authors.forename: John G
authors.initials: JG
authors.lastname: Yovos
mesh_terms: D000328:Adult; D000465:Algorithms; D002118:Calcium / Q000032:analysis / Q000097:blood*; D003940:Diagnostic Techniques, Endocrine / Q000592:standards; D005260:Female; D006801:Humans; D006996:Hypocalcemia / Q000097:blood / Q000209:etiology / Q000378:metabolism; D007262:Infusions, Intravenous; D008297:Male; D008875:Middle Aged; D010280:Parathyroid Glands / Q000378:metabolism* / Q000502:physiology; D010281:Parathyroid Hormone / Q000097:blood / Q000378:metabolism; D011184:Postoperative Period; D012016:Reference Values; D017693:Sodium Bicarbonate / Q000008:administration & dosage; D016606:Thyroid Nodule / Q000097:blood / Q000378:metabolism / Q000601:surgery*; D013965:Thyroidectomy / Q000379:methods / Q000534:rehabilitation*
chemical_list: D010281:Parathyroid Hormone; D017693:Sodium Bicarbonate; D002118:Calcium