Pseudopituitary dwarfism due to resistance to somatomedin: A new syndrome

The case of an infant is described who at birth was already small and postnatally grew extremely slowly. At age 3 the girl's height was 65 cm, weight 5.6 kg, bone age 21 months. Basal plasma GH was 36-66 ng/ml, basal SM activity was rather high, being around 2.0 U/ml. RIA- and RRA-SM were also increased. Prolonged GH administration did not raise plasma SM. There was a tendency for hypoglycemic episodes in the presence of low insulin levels. Receptor studies with skin fibroblasts showed a diminution of the specific binding of SM-C by 50%. Apparently only the specific IGF-receptor is defective whereas the insulin receptor responds to the increased SM with hypoglycemia. The observation that the high plasma SM did not suppress the enhanced GH-secretion suggests that perhaps the hypothalamic IGF-receptor was also defective.