Prevalence of adrenocorticotropin deficiency in children with idiopathic growth hormone deficiency.

We sought to determine the prevalence of ACTH deficiency in children with GH deficiency (GHD) of unknown etiology with and without TSH deficiency and to correlate the structural characteristics of the hypothalamic-pituitary region on magnetic resonance imaging (MRI) with TSH and ACTH status. The electronic medical records system of a children's hospital was used to identify all patients less than 18 yr of age with GHD. TSH and ACTH deficiency were defined as being present if the patient was prescribed replacement hormone therapy. The medical records of 236 GHD subjects were reviewed, and the results of their MRI scans were recorded. Ninety had hypothalamic-pituitary-adrenal axis testing, and nine were ACTH deficient (10% of those tested; 4% of all subjects). Twenty-one (9%) of 236 were TSH deficient. All of the ACTH-deficient subjects were also TSH deficient: eight of nine had a gross abnormality on MRI, and one did not have an MRI report in the medical record. We conclude that patients with GHD, normal thyroid function, and no gross abnormalities on MRI do not need hypothalamic-pituitary-adrenal testing because no ACTH-deficient subjects would have been missed using this strategy (95% confidence interval, 0-5%).