Radetti, G., Bui, F., Tonini, G., Bellone, J., Pagani, S., & Bozzola, M. (2004). Growth hormone (GH) isoforms following acute 22-kDa GH injection: Is it useful to detect GH abuse? International Journal of Sports Medicine, 25, 205-208.

This study investigated the influence of an acute administration of 22-kDa hGH (22-kDa GH) on 22-kDa GH and 20-kDa GH serum levels, biological activity of GH (Nb2-GH) and on 22-kDa/20-kDa GH ratio, in order to verify whether the assessment of the GH isoforms could be a potential tool for diagnosing GH abuse. Children (M = 21; F = 7) affected by idiopathic isolated GH deficiency and children (M = 8; F = 2), affected by constitutional growth delay, were evaluated. After an overnight fast, a basal blood sample was obtained between 8 - 9 AM. and a dose of 22-kDa GH was then administered subcutaneously (0.1U/Kg). Blood was drawn after 2, 4, and 6 hours, for the evaluation of 22-kDa GH, Nb2-GH and 20-kDa GH serum levels.

Similar results were obtained in patients and controls: a significant rise, although of variable amplitude, of 22-kDa GH and Nb2-GH was found and the maximum peak was detected after four hours in the majority of Ss. No acute changes in 20-kDa GH serum levels were observed. The 22-kDa/20-kDa GH ratio increased progressively, due to the rising levels of 22-kDa GH. A positive correlation was seen between 22-kDa GH and Nb2-GH levels at baseline and at 2, 4, and 6 hours. Since in normal subjects the ratio of endogenous 22-kDa GH and 20-kDa GH is constant, an altered ratio of 22-kDa/20-kDa GH is highly suggestive of GH abuse. The short period of time available for the evaluation however (within 3 hours from GH injection), severely limits this investigational tool in athletes.

Implication. This investigation suggests one possibility for detecting growth hormone abuse but it is severely limited by the three-hour period after GH injection in which it is feasible.

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