Detection of exogenous growth hormone (GH) administration by monitoring ratio of 20kDa- and 22kDa-GH in serum and urine.

We previously demonstrated that individual subjects have fairly constant ratios of serum concentrations of 20 kDa- (20K) and 22 kDa-GH (22K). The aim of this study is to demonstrate the possibility of utilizing the changes in the ratio of 20K/22K for detecting the exogenous administration of 22K. A male patient with idiopathic dilated cardiomyopathy (age 51) received 22K (4U, s.c.) every other day. The concentrations of 20K and 22K in serum and urine were measured using enzyme-linked immunosorbent assays before and after administration. The administration of 22K increased total GH concentration, and markedly decreased the ratio of 20K/22K in serum, especially 2-10 h after the administration. From calculations, it became clear that the concentration of exogenous 22K reached a peak between 2-4 h after the administration and decreased to a negligible level after 24 h. The ratio of 20K/22K in the 0-24 h urine was 5 times lower than that in the 24-48 h urine. These data suggest that, by monitoring the ratio of 20K/22K in serum or urine, it is possible to determine whether or not GH has been externally administered and to calculate the serum GH that has been administered.