Growth hormone insensitivity is a condition characterized by severe growth failure, in the presence of normal-to-elevated concentrations of circulating growth hormone and resistance to exogenous growth hormone therapy. Typical clinical features of the condition include a congenital growth failure, delayed bone age, frontotemporal hairline recession, bossing, hypoplastic nasal bridge, shallow orbits, hypomuscularity, walking delay, limited elbow extensibility, hypercholesterolemia, and delayed puberty with normal reproduction. In addition, children affected with Larson syndrome also show a form of primary immunodeficiency. This insensitivity to the growth hormone can arise from different etiologies including postreceptor defects.
Diagnosis of the condition requires a careful work-up, keeping in mind the various etiologies of the broader growth hormone resistance disease/growth hormone insensitivity. Unlike GHRD, hypoglycemia is usually not seen in the case of GHI. The only specific treatment available for affected patients is the administration of recombinant human insulin growth factor-I. It is important that patients who receive this form of therapy be monitored regularly for blood sugar variations. Additionally, a small proportion of such patients may also require a tonsillectomy/adenoidectomy as a result of the adverse effect of lymphoid hyperplasia. Long term prognosis is very good, with the exception of an increased risk for cardiovascular disease.