Luteinizing hormone is one of the many reproductive hormones that keep our bodies functioning properly. OBGYN Dr. Gleaton is here to explain what LH is, what LH levels should be expected, and how tracking LH can help you get pregnant.

 

By OBGYN and fertility expert Dr. Kenosha Gleaton

LH (luteinizing hormone) is a key hormone for both male and female reproductive systems- let’s talk about why tracking LH is beneficial to getting pregnant. 

What is LH, anyway?

There are a few key reproductive hormones— estrogen, progesterone, follicle stimulating hormone (FSH), human chorionic gonadotropin (hCG), and luteinizing hormone (LH) that impact menstruation, ovulation, and pregnancy.  

LH is the hormone released by the brain that tells your ovaries to release a mature egg, which is known as ovulation. 

What does LH tell you about your fertile window?

A woman’s fertile window is a short period of time surrounding ovulation when she’s able to conceive. A surge in the level of LH is what triggers ovulation. This can be detected using ovulation predictor tests or ovulation predictor kits (OPKs). If the test result is positive, it indicates that ovulation will occur in the next 24 to 48 hours. This represents the fertile window and is the ideal time to have intercourse if trying to conceive.

What is a normal LH level?

LH levels change widely throughout your cycle, and your life. LH levels can even fluctuate based on how diluted your urine is when you take the test. A baseline LH can be computed by taking the average of LH values for the five days immediately before the LH surge.

Baseline LH levels generally range from 1.9 - 14.6 IU/L, depending on where you are in your cycle. 

  • Follicular phase of menstrual cycle: 1.37 to 9 IU/L
  • Midcycle peak: 6.17 to 17.2 IU/L
  • Luteal phase: 1.09 to 9.2 IU/L

When is LH the lowest?

LH levels fluctuate during your cycle. When you’re not pregnant, the lowest point is typically during the early follicular phase when menstruation is occuring. At this point, LH blood levels generally range from 1.37 to 9 IU/L.

LH is also low during pregnancy, when levels are less than 1.5 IU/L. Read more in Does LH Surge Stay High if Pregnant?

When is LH the highest?

During your cycle, LH levels are highest about 10-12 hours before ovulation, and can reach 30 IU/L or higher. This is called the LH surge. 

It’s also common to see high LH levels during menopause, ranging from 19.3 to 100 IU/L. 

Is LH always present in your body?

Pretty much! Even men need LH (1.42 to 15.4 IU/L) to help produce testosterone, so there is always going to be a trace of LH in your body. 

  • Follicular phase of menstrual cycle: 1.37 to 9 IU/L
  • Midcycle peak: 6.17 to 17.2 IU/L
  • Luteal phase: 1.09 to 9.2 IU/L
  • Pregnancy: < 1.5 IU/L
  • Postmenopausal: 19.3 to 100.6IU/L

How do I track LH?

Taking an ovulation test is the easiest way to track LH at home. Ovulation tests measure LH levels in your urine to determine if you’re ovulating or not. Many such tests have two lines, the control  and the test line. . You can determine how much LH is in your urine by paying attention to how dark your test line is. If you get a positive result, you know your LH level has reached 25 IU/L, when the baseline level is usually between 2-14.5 IU/L

LH urine vs blood serum test

LH can be tested by blood serum (at your clinic) or with at-home ovulation tests. An LH surge appears in the urine within 12 hours after it appears in the blood. One study found that blood serum and urinary tests show excellent agreement and can be used interchangeably.

Keep in mind that with blood tests, each lab has a different range for what's normal. You should get a lab report showing the range that your lab uses for each test, and if your results fall into low, normal, or high. Talk to your doctor if you have any questions about your lab results. 

What if ovulation tests never show a positive result?

If you didn’t ovulate in your current or most recent cycle, you may be wondering if it’s going to happen again. It’s possible that you’ve experienced an anovulatory cycle, a fairly common occurrence that happens in about a third of normal menstrual cycles. Anovulatory cycles are nothing to be worried about and can occur from time to time. 

Try testing again next month to determine if you ovulate (you may want to start earlier and test for as many days as possible in case ovulation occurs earlier or later than expected). If you notice you haven’t ovulated in multiple consecutive cycles, you may want to talk to your doctor about what steps to take moving forward. 

When should I consult with a doctor?

If you’re trying to get pregnant and having difficulty conceiving, you may want to consult a fertility expert. For women under age 35, we recommend seeking help after 12 months of trying to conceive. For women over 35, we recommend a shorter time period: six months. 

You may want to seek help before then if you have irregular menstrual cycles, have experienced two or more miscarriages, have a family history of premature menopause, or a history of ovarian surgery or endometriosis.

Read more about when to see a fertility specialist → 

Take-aways

  • LH is a key reproductive hormone for both men and women
  • LH is a hormone released by the brain that triggers ovulation
  • LH levels are lowest during your period and highest about 10-12 hours before ovulation
  • Ovulation tests are a helpful way to track your LH levels and pinpoint your fertile window
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