Eagle Biosciences 17OH Progesterone Saliva ELISA Assay Kit is a competitive immunoenzymatic colorimetric method for quantitative determination of 17OH progesterone concentration in saliva. 17OH Progesterone Saliva ELISA Assay Kit is intended for research use only and not to be used in diagnostic procedures. Sample Types: saliva. Range: 20 - 1600 pg/ml. Sensitivity: 4.9 pg/ml. Time: 2.5 hours ? As with cortisol, serum 17α -OHP levels normally have an ACTH-dependent diurnal variation, with peak levels in the morning and a nadir at night. In addition, ovarian production of 17α -OHP increases during the luteal phase of the menstrual cycle, leading to serum levels which are several-fold higher than during the follicular phase. The level of 17OHP in saliva (pg/mL) is significantly lower than levels in the general circulation (ng/mL). Progesterone appears to prevent endometrial cancer by regulating the effects of estrogen. Measurement of circulating 17α -OHP levels is a standard tool for clinical assessment of 21-hydroxylase deficiency, the most common cause of congenital adrenal hyperplasia. Due to the decreased activity of 21-hydroxylase, 17α -OHP cannot be efficiently converted to cortisol and, instead, accumulates in large amounts and is shunted into the androgen biosynthetic pathway. 17α -OHP levels are useful in monitoring steroid replacement therapy.