Basal serum cortisol as a predictor for adrenal reserve in children with adrenal insufficiency

ABSTRACT

Background: Secondary adrenocortical insufficiency occurs in children who have been suffering from pathological conditions in the hypothalamo-pituitary region such as infection, irradiation, and after tumor removal. The basal serum cortisol level as a predictor of secondary adrenocortical insufficiency has been studied mostly in adult and rarely in children. The aim of this study is to evaluate the basal morning cortisol level as a predictor of secondary adrenocortical insufficiency. Material and method: Forty-nine children, aged 2-15 years, were recruited for this study. Forty-six had tumors in the suprasellar region, two had suprasellar arachnoid cysts, and one had a history of high dose cranial irradiation. In addition, 52 idiopathic short children with proven normal hypothalamo-pituitary function were a control group. Serum basal morning cortisol level (7.30-9.00 am) was measured, and then the insulin tolerance test (ITT) was performed as a gold standard in all children. Results: A basal morning cortisol level of less than 4 μg/dL suggested the diagnosis of secondary adrenocortical insufficiency with specificity of 100% and positive predictive value (PPV) of 100%. In addition, basal cortisol level of more than 18 μg/dL could exclude the secondary adrenocorticol insufficiency with specificity of 100% and PPV of 100%. The more additional pituitary hormone deficiency was, the less was serum basal cortisol level, which represented the potential severity of pituitary gland insult. Conclusion: Measurement of morning basal cortisol level finding less than 4 and more than18 μg/dL can predict the outcome of hypothalamo-pituitary reserve function with 100% PPV in order to avoid a complicated and risky ITT in children with pathology around suprasellar region.