Secreted proteins, which include growth hormone, insulin and EPO (erythropoietin), are used by the body as molecular messengers to pass signals from one part of the body to another.

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The new test is the latest weapon in WADA's arsenal following the development of tests for the endurance-boosting drug erythropoietin (EPO) and so-called designer steroids such as tetrahydrogestrinone (THG), which have been chemically engineered to deceive the testers.

CNN: Anti-drugs chief confirms HGH test

Eprex, Roche's NeoRecormon and Amgen's Epogen are all versions of the same hormone, erythropoietin, or EPO.

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