Endocrine Abstracts

Introduction: Hydrocortisone is the main treatment for congenital adrenal hyperplasia (CAH) in children. The optimal biochemical monitoring and replacement regimen of these children continues to be debated. We explored variations in blood spot 17α-hydroxyprogesterone (17-OHP) levels.

Methods: Single centre retrospective cross-sectional study of children with 21-hydroxylase deficiency aged <18 years. Patients treated with hydrocortisone who had dried blood spot 17-OHP levels measured between October 2014 and April 2018 were included. On sampling days, patients collect four blood spots on filter paper cards; one before each hydrocortisone dose and one at midnight. Most patients had multiple samples; the first sample in prepubertal patients and the last sample in postpubertal patients was selected. Clinical data at the time of sampling was recorded.

Results: Twenty children were included in the study; baseline characteristics and treatment specifics are shown in Tables 1 and 2.

In a linear regression model (independent variables: gender, puberty, BMI SDS and glucocorticoid dose), mean daily 17-OHP levels were negatively associated with total daily hydrocortisone dose (B=−18.4; P=0.036), positively associated with being postpubertal (B=147.3; P=0.013) and borderline negatively associated with BMI SDS (B=−31.0; P=0.087). However, morning 17-OHP levels were not associated with evening hydrocortisone dose nor with total hydrocortisone dose. Evening 17-OHP levels were borderline negatively associated with afternoon hydrocortisone dose (B=−47.3; P=0.086). Gender, age, height or phenotype were not associated with 17-OHP levels.

Conclusion: 17-OHP levels were negatively associated with total daily hydrocortisone dose and therapy could be titrated based on blood spot 17-OHP levels. Morning 17-OHP levels, however, are not associated with evening hydrocortisone dose. Therefore, our results do not support reverse circadian rhythm hydrocortisone therapy in children with CAH.