Abstract
A radioimmunoassay suitable for measurement of 17αOH-progesterone concentrations in small aliquots of plasma (20 μL), amniotic fluid (20 μL) and saliva (200 μL) is described. The assay features an antiserum raised against a 17αOH-progesterone-3-(O-carboxymethyl)oxime/BSA conjugate coupled to a magnetisable, solid-phase support; the homologous radioligand is a 125I-iodohistamine conjugate. This combination of a γ-emitting ligand and a magnetic-separation procedure has the advantage of reducing assay time and cost; it also allows processing of plasma and saliva samples in the same assay batch. The method has satisfactory sensitivity, precision and accuracy. Data derived from clinical studies of patients with congenital adrenal hyperplasia indicate the usefulness of this assay in routine practice.