Measurement of free IGF-I saliva levels: perspectives in the detection of GH/IGF axis in athletes.
OBJECTIVE
To examine an immunoassay for measuring free IGF-I in a saliva specimen (free sIGF-I) and to study the levels in relation to the training conditions comparing young athletes and sedentary females.


METHODS
The analysis was carried out by modifying a commercial kit for plasma matrix to measure the free sIGF-I. The plasma free and total IGF-I fractions, hGH and salivary total proteins were also measured. Saliva and blood specimens were collected from 15 well-trained young female volleyball athletes and from a control group of 14 young sedentary females.


RESULTS
The calibration curve to assay free sIGF-I covered the range 0.05-5.00 microg/L. The detection limit was 0.07 microg/L. The within-run and between-run imprecision CVs were 10% and 13% respectively. The average recovery was 88%. Free sIGF-I, measured in 15 athletes and in 14 young sedentary females, was 0.10+/-0.03 and 0.20+/-0.05 micarog/L respectively (p<0.001).


CONCLUSIONS
There were decreased levels of free sIGF-I in well-trained athletes, compared with sedentary females. This decrease could be related to a greater tissue requirement by the active muscle subjected to intense exercise for several days.
Antonelli
G
G
Section of Clinical Biochemistry, Department of Medical Diagnostic Sciences and Spec. Ther., University of Padua, c/o ex Istituto di Semeiotica Medica Via Ospedale 105, 35128 Padova, Italy.
Cappellin
E
E
Gatti
R
R
Chiappin
S
S
Spinella
P
P
De Palo
E F
EF
D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D015444:Exercise / Q000502:physiology*; D005260:Female; D019382:Human Growth Hormone / Q000032:analysis / Q000097:blood; D006801:Humans; D007118:Immunoassay / Q000379:methods; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D015203:Reproducibility of Results; D012463:Saliva / Q000737:chemistry*; D012471:Salivary Proteins and Peptides / Q000032:analysis*; D013177:Sports
D012471:Salivary Proteins and Peptides; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I