17-Hydroxyprogesterone rhythms and growth velocity in congenital adrenal hyperplasia

Six patients on steroid replacement therapy for congenital adrenal hyperplasia provided capillary blood samples collected at 0800, 1200, 1700, and 2200 h, on to filter paper for 17-hydroxyprogesterone analysis. There was a strong correlation between 17-hydroxyprogesterone day profiles and height velocity over a 4 year period of study. Steroid over-replacement, identified by significantly decreased height velocity (Standard Deviation Score [SDS] 1.92), caused suppression of 17-hydroxyprogesterone concentrations to below 10 nmol/L throughout the day. Near average height velocity (Standard Deviation Score 0.245) was accompanied by suppression of 17-hydroxyprogesterone concentrations below 40 nmol/L but with significant diurnal variation. Under-replacement with rapid height velocity and bone maturation was accompanied by non-suppression of 17-hydroxyprogesterone concentrations (i.e. > 40 nmol/L). These results suggest that serial blood spot 17-hydroxyprogesterone measurements are a convenient and helpful supplement to measurements of height velocity and bone age maturation to monitor steroid replacement therapy in congenital adrenal hyperplasia. These measurements may be useful particularly in differentiating between over-replacement and appropriate replacement, and should allow adjustments in dose before abnormal growth patterns are established.