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.