Increased Immunoreactive Plasma and Urinary Growth Hormone in Growth Retardation With Defective Generation of Somatomedin a (Laron's Syndrome)

Kastrup, K. W., Andersen, H. and Hanssen, K. F. (Childrens Hospital, Fuglebakken, and Steno Memorial Hospital, Copenhagen, Denmark). Increased immunoreac‐tive plasma and urinary growth hormone in growth retardation with defective somatomedin A generation (Laron's syndrome). Acta Paediatr Scand 64: 613, 1975.–In a boy 4 years old with clinical hypopituitary dwarfism, high plasma and urinary levels of immunoreactive growth hormone were found. Somatomedin A levels in serum were low and failed to respond after short‐term treatment with human growth hormone. The parents were first cousins. In the arginine and insulin tolerance tests the initially high immunoreactive growth hormone levels were later followed by a decrease to high normal values. Insulinopenic response was present during the arginine and glucose tolerance tests. As a growth hormone molecule defect is not found in these patients and no growth or other metabolic response to exogenous HGH can be demonstrated, it is concluded that a defective somatomedin generation may be present, probably in conjunction with a generalized receptor defect and deficient feedback system with abnormal release of HGH. The lack of somatomedin A is responsible for the severe growth retardation and the disturbance in carbohydrate metabolism is probably caused by sustained high growth hormone levels.