I am writing to you because I continue to be disturbed by the fact that many pediatric endocrinologists, including several leaders in the field, continue to ignore published papers casting serious doubts on the validity of the somatomedin hypothesis. The more recent publications of Salmon (whose experiments with Dr. Daughaday half a century ago led to the origins of the hypothesis) have essentially refuted the findings of those original publications, but many pediatric endocrinologists seem to have decided that they do not exist.

I enclose a brief article that I recently wrote summarizing the evidence against the hypothesis: the recent experiments of Salmon and Burkhalter, the experiments done by Derek LeRoith's group at the NIH showing that deletion of the hepatic gene for IGF-I did not impair growth in mice despite a 75% reduction in circulating concentrations of IGF-I; the demonstration that virtually all tissues have growth hormone receptors and do not depend on a circulating messenger to mediate its actions; and the fact that somatomedin is an insulin-like growth factor despite the fact that growth hormone is a counter-regulatory factor that opposes the actions of insulin.

Writings and oral presentations by prominent pediatric endocrinologists continue to cite as gospel the original Salmon and Daughaday papers as though they are unaware of the refutation of those experiments by Salmon and Burkhalter even though they have appeared in peer reviewed journals.

Perhaps Growth Genetics & Hormones, one of the most respected pediatric endocrine publications, might be able to do something about calling the attention of those in the field who need to reexamine the validity of the hypothesis.

Solomon A. Kaplan, MD