The role of auxologic and growth factor measurements in the diagnosis of growth hormone deficiency.

The use of auxologic measurements in the diagnosis of short stature in children has a long history in pediatric endocrinology, and they have even been used as the primary criteria in selecting children for growth hormone (GH) therapy. Certainly, an abnormality in the control of growth is more likely in short children than in children of normal stature. However, most studies have shown little or no value of auxologic criteria in differentiating short children who have classic growth hormone deficiency (GHD) from short children who do not. In National Cooperative Growth Study Substudy VI, in more than 6000 children being assessed for short stature, the overall mean height SD score was -2.5 +/- 1.1 and the body mass index standard deviation score was -0.5 +/- 1.4. However, there were no significant differences in these measures between the patients who were found subsequently to have GHD and those who were not. There also was no consistent difference in the growth rates between the patients with classic GHD and those short children without a diagnosis of GHD. This probably reflects the fact that we are dealing with a selected population of children who were referred for short stature and are further selecting those who are the shortest for additional investigation. Growth factor measurements have been somewhat more useful in selecting patients with GHD and have been proposed as primary diagnostic criteria. However, in National Cooperative Growth Study Substudy VI, only small differences in the levels of insulin-like growth factor I and insulin-like growth factor binding protein 3 were seen between the patients who were selected for GH treatment and those who were not. Many studies indicate that the primary value of growth factor measurements is to exclude patients who are unlikely to have GHD or to identify those patients in whom an expedited work-up should be performed. The diagnosis of GHD remains difficult and must be based on all of the data possible and the best judgment of an experienced clinician. Even under ideal circumstances, errors of both overdiagnosis and underdiagnosis of GHD still are likely.