Chronic glucocorticoid treatment alters spontaneous pulsatile parathyroid hormone secretory dynamics in human subjects.
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.
Bonadonna
Stefania
S
Department of Medical Sciences, University of Brescia, Brescia, Italy.
Burattin
Anna
A
Nuzzo
Monica
M
Bugari
Giovanna
G
Rosei
Enrico Agabiti
EA
Valle
Domenico
D
Iori
Nicoletta
N
Bilezikian
John P
JP
Veldhuis
Johannes D
JD
Giustina
Andrea
A
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
D005938:Glucocorticoids; D010281:Parathyroid Hormone; D014807:Vitamin D; D011239:Prednisolone; C104450:25-hydroxyvitamin D; D002118:Calcium