title: Chronic glucocorticoid treatment alters spontaneous pulsatile parathyroid hormone secretory dynamics in human subjects.
abstract: OBJECTIVE
  Spontaneous parathyroid hormone (PTH) secretory dynamics include tonic and pulsatile components. It is not known how glucocorticoids might alter these secretory dynamics.
  
  
  METHODS
  The aim of our study was to evaluate spontaneous fluctuations in serum PTH levels in six adult male patients (aged 31-64 years) receiving chronic (>6 months) therapy with glucocorticoids (daily dosage >7.5 mg of prednisone or dose equivalent of other corticosteroid) as compared with a control group of 10 age- and sex-matched normal subjects.
  
  
  METHODS
  Peripheral venous blood sampling was performed every 3 min for 6 h from 0900 to 1500 h. Plasma PTH release profiles were subjected to deconvolution analysis, a method that resolves measured hormone concentrations into secretion and clearance components, and to an approximate entropy (ApEn) estimate, that in turn provides an integrated measure of the serial regularity or orderliness of the release process.
  
  
  RESULTS
  In the glucocorticoid-treated group, the PTH tonic secretory rate was reduced (4.3+/-0.74 vs 8.8+/-1.4 pg/ml per min in controls, P = 0.017). There was, however, an increase in the fractional pulsatile PTH secretion (42+/-8.2 vs 18.3+/-3.9 pg/ml per min, P = 0.006) in glucocorticoid-treated vs normal subjects. Mean overall PTH concentration, as well as mean integrated area, was similar among normal and glucocorticoid-treated subjects.
  
  
  CONCLUSIONS
  These results demonstrate, for the first time, that chronic glucocorticoid treatment induces a redistribution of spontaneous PTH secretory dynamics by reducing the amount released in tonic fashion and increasing the amount released as pulses.
authors.affiliation: Department of Medical Sciences, University of Brescia, Brescia, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Bonadonna
authors.forename: Anna
authors.initials: A
authors.lastname: Burattin
authors.forename: Monica
authors.initials: M
authors.lastname: Nuzzo
authors.forename: Giovanna
authors.initials: G
authors.lastname: Bugari
authors.forename: Enrico Agabiti
authors.initials: EA
authors.lastname: Rosei
authors.forename: Domenico
authors.initials: D
authors.lastname: Valle
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Iori
authors.forename: John P
authors.initials: JP
authors.lastname: Bilezikian
authors.forename: Johannes D
authors.initials: JD
authors.lastname: Veldhuis
authors.forename: Andrea
authors.initials: A
authors.lastname: Giustina
mesh_terms: D000328:Adult; D001327:Autoimmune Diseases / Q000188:drug therapy* / Q000378:metabolism; D001842:Bone and Bones / Q000378:metabolism; D002118:Calcium / Q000097:blood / Q000652:urine; D005938:Glucocorticoids / Q000008:administration & dosage*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010280:Parathyroid Glands / Q000187:drug effects* / Q000378:metabolism*; D010281:Parathyroid Hormone / Q000378:metabolism*; D011239:Prednisolone / Q000008:administration & dosage*; D011673:Pulsatile Flow; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D005938:Glucocorticoids; D010281:Parathyroid Hormone; D014807:Vitamin D; D011239:Prednisolone; C104450:25-hydroxyvitamin D; D002118:Calcium