Monitoring Steroid Replacement Therapy in Children with Congenital Adrenal Hyperplasia

Background: The objective of this study was to compare the analysis of 17-hydroxyprogesterone (17-OHP) by radio-immunoassay (RIA) in serum with analysis by liquid chromatography tandem mass spectrometry (LC-MS/MS) on dried blood spot samples (DBSS) for monitoring therapy in children with congenital adrenal hyperplasia (CAH), and to investigate differences in 17-OHP values during the day.

Methods: Fourteen children (8 females), median age 4.2 (0.3-16.0) years, were studied. Serum samples and DBSS were drawn before hydrocortisone dosing.

Results: 17-OHP by LC-MS/MS in DBSS were highly correlated to 17-OHP by RIA in serum, r=0.956, p<0.01. A total of 26 three-time-point series were investigated. Using only the afternoon 17-OHP values to determine the hydrocortisone doses would have led to overdosing seven times and underdosing six times.

Conclusions: Good agreement was demonstrated between 17-OHP determination by RIA in serum and LC-MS/MS on DBSS. Multiple 17-OHP measurements per day are required to ensure sufficient hydrocortisone dose adjustment.