Urinary insulin-like growth factor-I measurement in an actual sport competition, an additional approach in laboratory antidoping tests

Clin Chim Acta. 2005 Jan;351(1-2):73-8. doi: 10.1016/j.cccn.2004.06.023.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Bicycling / physiology*
  • Creatinine / urine
  • Doping in Sports*
  • Exercise / physiology
  • Female
  • Humans
  • Insulin-Like Growth Factor I / urine*
  • Male
  • Proteinuria / etiology
  • Reagent Kits, Diagnostic

Substances

  • Reagent Kits, Diagnostic
  • Insulin-Like Growth Factor I
  • Creatinine