Predict fertile days. An ovulation predictor kit (opk) test detects lh hormone in your urine which is a signal you're going to ovulate (release an egg) in the next 24 - 36 hours. If you have regular periods, test between 10 am and noon, starting on day 10 of your cycle. The day of a positive test and the next 2 days are your most fertile days. With irregular periods you're not ovulating regularly: see a rei md for help.
Timing egg release . Ovulation predication refers to determining when the egg will release. Most people think of this the use of urinary test kit to check for ovulation. The opk measures a rise in the hormone lh in the urine, and a positive kit usually precedes ovulation by a day. Ovulation can also be predicted by charting out cycles, ultrasound and other methods.