Urinary insulin-like growth factor-I measurement in an actual sport competition, an additional approach in laboratory antidoping tests.
BACKGROUND
The insulin-like growth factor hormone (IGF-I) is an important protein hormone under investigation with physical exercise and for doping detection. Urinary IGF-I level in fact represents a relevant measurement when the postexercise proteinuria is under analysis. To verify the IGF-I level variation in the circulation and in urinary excretion in the occasion of a competition, the plasma and urine IGF-I in athletes before and after an actual competitive event were measured.


METHODS
Twenty well-trained cyclists took part in a competition (102 km) and concluded the intense physical exercise in approximately 2(1/2) h. Urine and blood samples were collected from each athlete 10-20 min before and at the end of the competition. Plasma and urine total IGF-I (pIGF, uIGF), total urinary proteins (uPr), and creatinine (uCr) concentrations were measured.


RESULTS
The uIGF [from 76.2+/-15.8 to 256.9+/-29.1 ng/l (p<0.001)], uPr [from 29.4+/-6.7 to 325.9+/-95.1 mg/l (p<0.005)], and uCr [from 6.3+/-1.0 to 10.0+/-0.8 mmol/l (p<0.005)] significantly increased. The pIGF was 262.6+/-14.3 and 247.3+/-11.8 microg/l before and end-exercise, respectively. A statistical correlation between uIGF and uPr was demonstrated (p<0.001). The pIGF/uIGF ratio was significantly (p<0.05) decreased comparing the end with before the competition.


CONCLUSIONS
The pIGF/uIGF significantly decreased at the end, compared with before the competition, suggesting a changed uIGF excretion. This increment appeared to be increased, although not significantly, considering the ratio with uCr.
De Palo
Elio F
EF
Section of Clinical Biochemistry, Department of Medical Diagnostic Sciences and Special Therapies, University of Padova, Via Ospedale 105-35128, Padova, Italy. eliof.depalo@unipd.it
Gatti
Rosalba
R
Lancerin
Federica
F
Cappellin
Enrico
E
De Palo
Carlo B
CB
Spinella
Paolo
P
D000293:Adolescent; D001642:Bicycling / Q000502:physiology*; D003404:Creatinine / Q000652:urine; D004300:Doping in Sports; D015444:Exercise / Q000502:physiology; D005260:Female; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000652:urine*; D008297:Male; D011507:Proteinuria / Q000209:etiology; D011933:Reagent Kits, Diagnostic
D011933:Reagent Kits, Diagnostic; D007334:Insulin-Like Growth Factor I; D003404:Creatinine