Question

What hormone(s) in the urine do over-the-counter ovulation predictor kits, fertility monitors, and early pregnancy tests (EPTs) measure? How soon after conception can EPTs be performed?

Answer 1

During the ovulation phase (14th day of cycle) estrogen levels peak causing a LH and FSH surge resulting in the rupture of the follicles and the release of the oocyte from the ovary. This lasts for 24-36 hours. If no fertilization occurs, the egg (oocyte) will degenerate between 12-24 hours of ovulation.

The growth of the egg or the ovum is under the influence of a hormone called the FSH or the follicular stimulating hormone. When the process of ovulation occur another hormone known as the LH or the luteinizing hormone is known to increase.

Luteinizing Hormone (LH) triggers ovulation in response to the estrogen mediated feedback from negative to positive creating a LH-mid cycle surge. This activates an inflammatory response in the dominant follicle and leads to the breakdown of the follicular boundary and escape of the oocyte.

Other hormones include

1. Gonadotropin releasing hormone (GnRH)

2. Follicle stimulating Hormone (FSH)

FSH and LH induce the production of estrogen and progesterone from the ovary which through a feedback mechanism influence the release of GnRH from the hypothalamus.

The principle behind the ovulation test kit is to detect the surge in the LH in the sample through an anti LH antibody contained in a sensitive testing membrane of the test.

Successful fertilization is likely to take place once there is a surge in the LH between 1-3 days. This ovulation window occurs once in a month.

In the ovulation test kit the two bands C and T refer to the control and the test bands. The reaction period for the test is 5 minutes. A positive test results in a test band with equal or greater intensity than the control band indicating the surge in the hormone LH.

A negative test results indicates that the level of LH is near or near to normal and the test band appears lighter or lesser intensity than the control band.