A case report of growth attenuation during methionyl human growth hormone treatment.

A 10-year-old child with idiopathic growth hormone deficiency was treated with recombinant methionyl human growth hormone (m-hGH, Somatonorm) at a dose of 14 IU/week. Height increased from 122.3 to 126.5 cm during the first 9 months of treatment (5.6 cm/y), but only from 126.5 to 126.6 cm during the next 3 month of treatment (0.4 cm/y). Anti-hGH antibody was detected at 2 months of treatment, reached its maximum at the end of 9 months with a titer of 10(6) and a binding capacity of 2.0 mg/L. After switching from m-hGH to pituitary extracted hGH (p-hGH) treatment, his height increased again from 126.6 to 132.2 cm during the next 12 months of p-hGH treatment (5.6 cm/y). The cause of growth attenuation during m-hGH treatment was concluded to be the high titer of anti-hGH antibody. This is the first case in Japan and one of only three cases in which growth attenuation occurred during m-hGH treatment.