title: Acute parathyroid hormone increase by oral peptones administration after roux-en-Y gastric bypass surgery in obese subjects: role of phosphate in the rapid control of parathyroid hormone release.
abstract: BACKGROUND
  It is generally considered that changes in serum phosphate levels do not alter parathyroid hormone (PTH) secretion in the absence of concomitant changes in ionized serum calcium level in humans. An acute rise in PTH was shown after phosphate administration by intraduodenal gavage in rats. We aimed to study gastrin, phosphate, PTH, ionized calcium (iCa), and blood pH responses to oral peptones in morbidly obese patients before and after roux-en-Y gastric bypass (RYGB) surgery.
  
  
  METHODS
  These parameters were evaluated in response to an oral peptone load in 24 (18 male and 6 female) obese subjects before and 6 months after RYGB surgery. In 12 gastric bypass patients, we also evaluated PTH and phosphate after peptones plus aluminum hydroxide administration to suppress phosphate absorption.
  
  
  RESULTS
  Before RYGB, peptones increased gastrin (P < .001), and decreased iCa (P < .01) without changes in PTH or pH. Both phosphate and PTH markedly increased after RYGB with the peptones oral load (P < .01), without changes in pH, iCa, or gastrin. There was a significant, direct relationship between the increase of phosphate and the increase of PTH in the patients treated with aluminum hydroxide (r(2) = 0.78; P < .0001).
  
  
  CONCLUSIONS
  Rapid delivery of peptones in the jejunum in bypassed obese patients results in a significant rise in phosphate and PTH, in the absence of changes of other PTH regulators, possibly mediated by a signaling from the gastrointestinal tract. RYGB patients provide an opportunity to study the control of PTH secretion, with potential relevant clinical implications.
authors.affiliation: Endocrinology and Diabetes Unit, Luigi Sacco Hospital (Vialba), University of Milan, Milan, Italy. bevilacqua.maurizio@hsacco.it
authors.forename: Maurizio
authors.initials: M
authors.lastname: Bevilacqua
authors.forename: Ligia J
authors.initials: LJ
authors.lastname: Dominguez
authors.forename: Velella
authors.initials: V
authors.lastname: Righini
authors.forename: Tarcisio
authors.initials: T
authors.lastname: Vago
authors.forename: Diego
authors.initials: D
authors.lastname: Foschi
authors.forename: Fabio
authors.initials: F
authors.lastname: Corsi
authors.forename: Emilio
authors.initials: E
authors.lastname: Trabucchi
authors.forename: Enrica
authors.initials: E
authors.lastname: Chebat
authors.forename: Maria
authors.initials: M
authors.lastname: Del Carmen Borghi
authors.forename: Gian Marco
authors.initials: GM
authors.lastname: Diana
authors.forename: Massimo
authors.initials: M
authors.lastname: Barrella
authors.forename: Mario
authors.initials: M
authors.lastname: Barbagallo
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000536:Aluminum Hydroxide / Q000008:administration & dosage; D002118:Calcium / Q000097:blood; D005260:Female; D015390:Gastric Bypass; D005755:Gastrins / Q000097:blood; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007408:Intestinal Absorption / Q000187:drug effects; D007583:Jejunum / Q000378:metabolism; D008297:Male; D009767:Obesity, Morbid / Q000188:drug therapy / Q000378:metabolism / Q000601:surgery; D010281:Parathyroid Hormone / Q000097:blood* / Q000378:metabolism; D010461:Peptones / Q000008:administration & dosage*; D010710:Phosphates / Q000097:blood* / Q000493:pharmacokinetics; D011184:Postoperative Period; D011446:Prospective Studies; D055815:Young Adult
chemical_list: D005755:Gastrins; D010281:Parathyroid Hormone; D010461:Peptones; D010710:Phosphates; D000536:Aluminum Hydroxide; D002118:Calcium