308 DWARFISM DUE TO IMMUNOREACTIVE BUT BIOLOGICALLY INACTIVE GROWTH HORMONE

Abstract

In the syndrome of familial dwarfism with high plasma immunoreactive growth hormone (GH)(Laron Syndrome), elevated levels of GH are associated with low levels of plasma somatomedin that do not increase following administration of GH. These patients do not respond to treatment with GH.The two subjects of this report were three-year-old boys with dwarfism (height ages 1 3/12 and 1 6/12 years) and delayed bone ages (1 3/12 and 1 9/12 years). Both had normal GH response after stimulation associated with undetectable levels of somatomedin. However, unlike patients with Laron Syndrome, the two patients generated normal levels of somatomedin after intra-muscular administration of GH. Treatment with GH (2 IU every other day) brought a significant increase in the growth rate of both patients. The growth rate of the first patient increased from 2 cm/year before treatment, to 16 cm/year on therapy. The growth rate of the second patient was 4.5 cm/year before treatment, and 11.0 cm/year while on treatment.The two cases represent a new syndrome of dwarfism due to biologically inactive, immunoreactive GH. If erroneously diagnosed as having Laron Syndrome, these patients may be denied the benefit of treatment.