Tracking growth hormone abuse in sport: A comparison of distinct isoform-based assays

Determination of Recent Growth Hormone Abuse Using a Single Dried Blood Spot

BACKGROUND

Although it is being increasingly applied, blood collection for drug testing in sport presents some logistic issues that complicate full applicability on a large scale. The use of dried blood spots (DBS) could benefit compliant blood testing considerably owing to its simplicity, minimal invasiveness, analyte stability, and reduced costs. The aim of this study was to evaluate the applicability of DBS to the methodology approved by the World Anti-Doping Agency (WADA) for detection of doping by recombinant human growth hormone (rhGH) in serum.

METHODS

A protocol for a single DBS analysis using the hGH isoforms differential immunoassays (kit 1 and kit 2) was developed and validated. A clinical study with healthy volunteers injected for 3 consecutive days with a low subcutaneous dose (0.027 mg · kg−1 · day−1 · person−1) of rhGH was conducted. Finger prick DBS and paired-time serum samples from arm venipuncture were compared.

RESULTS

The analysis of the DBS-based protocol indicated that with only a single blood spot it was possible to detect positivity for growth hormone abuse. In spite of the low rhGH dose administered and independently of the kit used, the window of detection for DBS was confirmed in all analyzed samples up to 8 h after rhGH administration and extended up to 12 h in 50% of the cases. Serum positivity was detected in all studied samples for 12 h after administration.

CONCLUSIONS

These results support the usefulness of DBS as a biological matrix for testing recent growth hormone abuse.

The effect of a period of intensive exercise on the isoform test to detect growth hormone doping in sports

OBJECTIVE

The major objective of this study was to investigate the effects of several days of intense exercise on growth hormone (hGH) testing using the World Anti-Doping Agencies hGH isoform differential immunoassays. Additionally the effects of circadian variation and exercise type on the isoform ratios were also investigated.

STUDY DESIGN

15 male athletes performed a simulated nine day cycling stage race. Blood samples were collected twice daily over a period of 15 days (stage race+three days before and after). hGH isoforms were analysed by the official WADA immunoassays (CMZ Assay GmbH).

RESULTS

All measured isoform ratios were far below the WADA decision limits for an adverse analytical finding. Changes in the isoform ratios could not be clearly connected to circadian variation, exercise duration or intensity.

CONCLUSIONS

The present study demonstrates that the hGH isoform ratios are not significantly affected by exercise or circadian variation. We demonstrated that heavy, long term exercise does not interfere with the decision limits for an adverse analytical finding.

Analysis of urinary human growth hormone (hGH) using hydrogel nanoparticles and isoform differential immunoassays after short recombinant hGH treatment: preliminary results

Successful application clinical-grade human growth hormone (hGH) immunoassays to the discovery of illegal doping cases has been rare. Indeed, the preferred biological matrix in doping control is urine, where the estimated baseline concentration of hGH falls well below the linear range and sensitivity threshold of all commercially available immunoassays, including hGH isoform differential immunoassays which can discriminate pituitary endogenous hGH from recombinant hGH. We employed hydrogel nanoparticles as a pre-processing step that concentrate urinary hGH into the linear range of isoform differential immunoassays. We explored the characteristics of immunoassays in urine spiked with both phGH or rhGH, after pre-treatment with the nanoparticles. Subsequently, pre-treatment was applied to urine obtained from 3 healthy volunteers administered during three days with daily subcutaneous injections of 0.026 mg/kg/day rhGH, Genotonorm(®). Linearity between both rhGH and phGH concentrations in urine measured by a chemoluminescent assay (Immulite) and in the particle eluate was evident for differential immunoassays (R square higher than 0.999). In case of treated individuals the recombinant/pituitary concentration ratios remained above the established World Anti-Doping Agency (WADA) criterion for hGH misuse up to 24h after the last administration dose, using both assays for volunteer 1 and 2 while in case of volunteer 3 results were inconclusive. The use of nanoparticles appears to open the possibility of assessing rhGH misuse in urine.