Special remarks:

1. INTENDED USE

Enzyme immunoassay for the in-vitro diagnostic quantitative determination of 17-OH-progesterone in human serum and plasma.

2. SUMMARY AND EXPLANATION

The steroid hormone 17-OH-progesterone (17-OHP) is produced in the adrenal cortex and in the gonads. Gestagenic effects exerted by 17-OHP are only small. Nevertheless, this hormone is of clinical significance because it represents the ultimate precursor of 11b-desoxycortisol (compounds, CpS). CpS is formed by hydroxylation of the carbon atom C 21. Enzyme activity of 21-hydroxylase in the adrenal cortex may thus be monitored by analyzing the level of 17-OHP in the blood.

Deficiencies in 21-hydroxylase, most commonly found in congenital adrenal hyperplasia, result in excessive secretion of 17-OHP and consequently in enhanced blood levels. Deficiencies in 11-hydroxlase, however, merely lead to moderately increased values of 17-OHP. The analysis of this steroid hormone, therefore, plays a significant role in the differential diagnosis of congenital adrenal hyperplasia.

In adult non-pregnant women, 17-OHP levels in the blood depend on the phase of the menstrual cycle. Like progesterone, 17-OHP is secreted by the mature follicle and the corpus luteum. Concentrations are generally higher after ovulation.

In addition, levels of 17-OHP are influenced by daytime rhythms which correlate with the adrenal secretion of cortisol. Maximal levels are found in samples collected between midnight and 8.00 a.m..

In adult men, there are few indications of similar fluctuations of 17-OHP levels.

During pregnancy, large amounts of 17-OHP are produced by the fetus, the placenta and the adrenal cortex. The hormone is secreted into the fetal and the maternal blood circulation. Maternal values of 17-OHP

strongly increase after the 32. week of pregnancy reaching 4-fold higher levels than during the luteal phase of the menstrual cycle. 17-OHP may also be found in the umbilical cord of newborns.

3. TEST PRINCIPLE

Solid phase enzyme-linked immunosorbent assay (ELISA) based on the competition principle. An unknown amount of antigen present in the sample and a fixed amount of enzyme labeled antigen compete for the binding sites of the antibodies coated onto the wells. After incubation the wells are washed to stop the competition reaction. After the substrate reaction the intensity of the developed colour is inversely proportional to the amount of the antigen in the sample. Results of samples can be determined directly using the standard curve.