The study looked at ways to spot illegal growth hormone use by checking blood for certain genes and proteins, not by testing the hormone itself. It found that changes in the FN1 gene and protein, and the RAB31 gene, could signal recent growth hormone intake, and that a common growth‑hormone‑releasing peptide (GHRP‑2) doesn’t mess up these signals. This is mainly useful for anti‑doping labs, not for people who take GHRP‑2 to boost performance.

Human Growth Hormone (hGH, somatotropin) is one of the relevant forbidden substances to be detected in sport drug testing. Since the appearance of recombinant hGH (rhGH) in the 80's, its expansion and availability through the black market have increased, so the detection of its abuse continues to be a challenge at present. New techniques or biomarkers that are robust, reliable, sensitive and allowing a large detection time window are welcome. rhGH produces an increase of insulin-like growth factor 1 (IGF-1). FN1 (fibronectin 1) and RAB31 (member of RAS oncogene family) genes have been suggested as two potential biomarkers for IGF-1 abuse. Following this line, in the present study some genetic and proteomic approaches have been performed with fourteen healthy male subjects treated with rhGH (which produces increase of IGF-1 concentrations) to study FN1 gene, FN1 protein, RAB31 gene and RAB31 protein as potential biomarkers for rhGH abuse. The results showed that both, RAB31 and FN1 genes and FN1 protein could be potential biomarkers for rhGH administration. Preliminary assessments of gender, age, acute sport activities and GHRP-2 (pralmorelin, a rhGH releasing peptide) influence suggest they are not relevant confounding factors. Thus, the selected markers present high sensitivity and a larger detection window for rhGH detection than IGF-1 itself.