Radioimmunoassayof 17a-Hydroxyprogesteronein Saliva, Parotid

We report a radioimmunoassay sensitive enough to de-termine 17a-hydroxyprogesterone concentrations in 200 zL of parotid fluid or mixed whole saliva. Because the correlation of concentrations in matched samples of parotid fluid and saliva was excellent (r = 0.98), we ex-clusively used saliva, which is easier to collect, in later studies. The assay is specific; saliva samples assayed with and without thin-layer chromatographic purification showed no significant difference. The assay is also precise, and has a lower limit of sensitivity of 4 pg per assay tube. In 14 patients having congenital adrenal hyperplasia from a C21-hydroxylase enzyme deficiency, all of whom were receiving cortisol replacement therapy, the range in 17a-hydroxyprogesterone concentrations observed in saliva (67-26 300 pmol/L) was about 20-fold that seen i