OPK vs. LH test: What is the difference?

Have you ever found yourself utterly confused by OPKs and LH tests? If so, I promise you are not the first (or last) person to be confused by this.

Let’s talk about it!

OPK tests

An OPK, ovulation predictor kit, may also be called an ovulation test. It is testing the urine for the luteinizing hormone (LH). Usually, women use these when trying to conceive.

The hormone, LH, surges 24-36 hours before ovulation. Because of this, testing it in the urine can help anticipate ovulation. Hence the name ovulation predictor kit.

LH tests

LH tests are the SAME thing!! The only difference is how companies label their products— either for marketing purposes or ease of understanding.

It is comparable to the difference between Tylenol and Acetaminophen. They are the same drug-- just sold under different names.

Usually, women seek out this test under the name "LH test" when using it as a biomarker for fertility awareness. The goal is the same-- looking for the time of ovulation. However, rather than using that knowledge to plan for pregnancy, it is used to avoid pregnancy.

Timing of Ovulation

While testing for LH can help narrow down the time of ovulation, it is just an estimate. LH tests, in isolation, cannot confirm ovulation. The best way to determine the precise time of ovulation is through an ultrasound.

LH is responsible for telling the follicle on the ovary to rupture. Some people may see a positive LH test but do not go on to ovulate.

So there you have it! An OPK and a LH test are the exact same thing-- the only "difference" is in the name!