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 ra tios 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 ( 4 U, s.c.) every other day. The concentrations of 20K and 22K in serum and urine were measured using enzyme-linked immunosorbent assays before and aft er administration. The administration of 22K increased total GH concentrati on, and markedly decreased the ratio of 20K/22K in serum, especially 2-10 h after the administration. From calculations, it became clear that the conc entration of exogenous 22K reached a peak between 24 h after the administra tion and decreased to a negligible level after 24 h. The ratio of 20K/22K i n 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 administere d and to calculate the serum GH that has been administered.