Abstract
A bloodspot assay for testosterone has been developed using an antiserum raised against testosterone-3-carboxymethyloxime-bovine serum albumin (T-3 CMO-BSA) conjugate and 125I-T-3CMO-histamine tracer. The method has a detection limit of 0·4 nmol/L with between-batch precision of less than 15% for testosterone values between 0·9 and 2·0 nmol/L and less than 10% for values greater than 2·0 nmol/L. Recovery of 4 nmol/L testosterone spiked into whole blood samples from 16 women (with unspiked bloodspot testosterone concentrations ranging from 0·4 to 3·7 nmol/L) was 100·9%. Bloodspot testosterone concentration was measured in thirty 6–9 day old infants (19 boys, 11 girls) with an absolute range in boys of < 0·4–2·3 nmol/L and in girls of < 0·4 nmol/L. In preterm infants (12 boys, 12 girls) of varying birth gestation and postnatal age, levels were higher than in term infants, with boys showing a rise with increasing postnatal age. Daytime bloodspot profiles in four children on replacement therapy for congenital adrenal hyperplasia demonstrated consistently low testosterone levels in the presence of moderately elevated early morning 17-hydroxyprogesterone concentrations, thus indicating adequate treatment. The bloodspot testosterone assay can be applied to the study of androgen physiology in preterm neonates as well as for monitoring treatment in disorders such as congenital adrenal hyperplasia.