Measurement of free IGF-I saliva levels: perspectives in the detection of GH/IGF axis in athletes

Clin Biochem. 2007 May;40(8):545-50. doi: 10.1016/j.clinbiochem.2007.01.014. Epub 2007 Jan 26.


Objectives: 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.

Design and 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Case-Control Studies
  • Exercise / physiology*
  • Female
  • Human Growth Hormone / analysis
  • Human Growth Hormone / blood
  • Humans
  • Immunoassay / methods
  • Insulin-Like Growth Factor I / analysis*
  • Reproducibility of Results
  • Saliva / chemistry*
  • Salivary Proteins and Peptides / analysis*
  • Sports


  • Salivary Proteins and Peptides
  • Human Growth Hormone
  • Insulin-Like Growth Factor I