Luteinizing Hormone (LH) Test

two woman looking at a screen together

What is Luteinizing Hormone (LH)?

Produced by your pituitary gland, luteinizing hormone (LH) is vital for reproduction. LH helps regulate your menstrual cycle and ovulation. A rise in LH — called the LH surge — triggers ovulation.

Why Would I Have My LH Levels Checked?

Your LH levels can be used to determine when you’re ovulating. This information can help you plan out when to have intercourse with your partner if you’re trying to become pregnant.

If you’re having trouble becoming pregnant, you’ll probably have your LH levels checked. When measured along with FSH and estradiol, your LH gives your fertility doctor information about your ovarian reserve.

If you’re not ovulating, your LH levels can help determine the cause. For example, LH is typically elevated in patients with Polycystic Ovarian Syndrome (PCOS).

LH can also be used to:

  • Monitor your response to ovarian stimulation.
  • Predict the timing of ovulation.

If you’re not getting your period, or if you’re having irregular menstrual cycles, you may want to have your LH and other hormones checked, to look for potential problems.

When Should I Have My LH Levels Checked?

You should have your LH level checked at the beginning of the cycle — classically Day 3 — along with your FSH, to evaluate for ovarian function.

More commonly, the LH level should be checked midway through your cycle — Day 14 of a 28-day cycle. This is because the LH surge triggers ovulation.

What Does the LH Test Look For?

The LH test measures the amount of LH in the blood or urine. If your LH levels are high, it could mean a number of things. For example, high levels of LH are normal if you’re in menopause.

However, if you’re younger than 40, high LH levels could suggest:

  • Premature menopause.
  • Polycystic Ovary Syndrome (PCOS)
  • A genetic or congenital condition that affects the production of hormones.
  • High levels at times outside of the LH surge can interfere with ovulation and menstruation, contributing to infertility.

If your LH levels are low, you may not be getting your period. Because LH triggers ovulation, low levels of LH can prevent ovulation, and thus pregnancy.

Low levels of LH are common in:

  • Women with eating disorders.
  • Female athletes.
  • Women with high levels of stress.
  • Disorders of the pituitary gland or hypothalamus.

LH testing is usually done in conjunction with other hormone tests, such as FSH, testosterone, estradiol, and progesterone. The results of these other tests will help determine the next steps in your fertility treatment.

Dr. Alan Copperman is a board-certified reproductive endocrinologist and infertility specialist with a long history of success in treating infertility and applying fertility preservation technologies. He serves as Medical Director of Progyny, a leading fertility benefits management company, and co-founded and serves as Medical Director of RMA of New York, one of the largest and most prestigious IVF centers in the country. Dr. Copperman is also the Vice Chairman and Director of Infertility for the Icahn School of Medicine at Mount Sinai, and Chief Medical Officer of Sema4, a health information company. Dr. Copperman has been named to New York magazine’s list of Best Doctors 17 years in a row. He has been recognized by his peers and patient advocacy organizations for his commitment to patient-focused and data-driven care. He has published more than 100 original manuscripts and book chapters on reproductive medicine and has co-authored over 300 scientific abstracts on infertility, in vitro fertilization, egg freezing, ovum donation, and reproductive genetics.