A Bloodspot Androstenedione Assay Suitable for Home-Monitoring of Steroid Replacement Therapy in Congenital Adrenal Hyperplasia

Abstract

A bloodspot assay has been developed using an antiserum raised against androstenedione-3-carboxymethyloxime-bovine serum albumin (AD-3CMO-BSA) conjugate and 125I-AD-3CMO-histamine tracer. The method has a detection limit of 0·6 nmol/L blood and a working range from 0·6 to 40 nmol/L blood. The between-batch precision ranged from 8·4% to 23·3%. Bloodspot androstenedione (AD) concentrations were measured in 50 neonates (26 male, 24 female) and in 95 children (54 male, 41 female) aged 6 months to 18 years. No sex difference in concentrations was found in neonates, in pre-pubertal children up to 8 years of age, in pubertal children (males 8–16 years, females 8–14 years) or post-puberty. Bloodspot AD concentrations ranged from <0·6 to 2·7 nmol/L in neonates, <0·6 nmol/L in pre-pubertal children, 0·6–2·1 nmol/L in pubertal children and < 0·6–4·6 nmol/L post-puberty. Daytime bloodspot profiles in 10 children on replacement therapy for congenital adrenal hyperplasia generally showed good correlation between 17α-hydroxyprogesterone and AD concentrations ( r = 0·928, P < 0·001). Bloodspot AD profiles have advantages over 17α-hydroxyprogesterone profiles for the assessment of the adequacy of glucocorticoid replacement therapy.