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Hormone health

Luteinizing Hormone

Also known as: Serum LH tes

Luteinizing hormone (LH) is made by the anterior pituitary gland and works closely with follicle-stimulating hormone (FSH) to regulate the reproductive system. In women, LH plays a crucial role in triggering ovulation — which happens when the ovary releases a mature egg — and stimulating the corpus luteum to produce progesterone during the luteal phase of the menstrual cycle.

Because LH levels fluctuate throughout the cycle, the timing of the test is important. To determine a baseline level, collecting a sample on day 3 of the cycle is best. To pinpoint levels during the LH surge, which typically occurs about 34–36 hours before ovulation, you can test midway through your cycle. Consistently low LH  levels may indicate pituitary or hypothalamic dysfunction, while persistently high LH in women of reproductive age may point to polycystic ovary syndrome (PCOS). After menopause, when ovarian hormone production declines, LH levels remain elevated, similar to FSH.

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Key takeaways

  • Sample required: Blood

  • Tests for: Evaluates ovarian function, menstrual cycle regulation, ovulation, fertility, and menopause status by measuring luteinizing hormone, a gonadotropin that the pituitary gland produces

  • Healthy range: The typical range in women is 0.5 to 76.3 milli-international units per milliliter (mIU/mL), but reference values depend on age, where you are in your menstrual cycle, and whether or not you’re going through perimenopause or in menopause

What can an LH test tell you?

An LH test — usually in the context of other labs — offers insights into reproductive function. Your provider may order an LH test to:

  • Evaluate infertility. A mid-cycle LH surge confirms ovulation is near, so testing LH helps determine if ovulation is occurring.

  • Assess irregular or absent cycles. Abnormal LH patterns may point to PCOS, hypothalamic dysfunction, or pituitary issues.

  • Confirm menopause. High LH and FSH levels with low estradiol levels indicate a decline in ovarian function during menopause.

  • Monitor treatment. Providers may check LH during assisted reproduction treatments.

What is being tested?

The LH test measures the body’s amount of luteinizing hormone, a gonadotropin that the anterior pituitary gland releases in response to gonadotropin-releasing hormone (GnRH) from the hypothalamus. LH works alongside FSH to regulate ovulation, corpus luteum function, and sex hormone production.

Here’s how it works in each cycle phase:

  • In the follicular phase. LH circulates at lower levels, working alongside FSH to stimulate ovarian follicles as they grow and mature.

  • Mid-cycle (ovulation). A sharp surge in LH triggers the ovary to release a mature egg.

  • In the luteal phase. After ovulation, LH levels drop but remain essential for supporting the corpus luteum, which produces progesterone to stabilize the uterine lining.

  • Postmenopause. With the loss of estrogen and progesterone feedback from the ovaries, LH levels stay consistently elevated.

The body secretes LH in pulses in various concentrations throughout the menstrual cycle, so it’s important to interpret results in the context of when the test took place.

Where is the LH test typically included?

LH is not included in general health panels like the basic metabolic panel (BMP) or comprehensive metabolic panel (CMP). Providers may order LH as part of:

  • Fertility evaluations. With FSH, estradiol, and progesterone. Menstrual irregularity workups. With thyroid tests, prolactin, and pelvic ultrasound.

  • Menopause assessments. With FSH and estradiol to confirm ovarian insufficiency.

  • PCOS investigations. With testosterone, anti-Müllerian hormone (AMH), and prolactin.

Who should get an LH test?

A provider may recommend LH testing if you have:

  • Infertility. To monitor ovulation or ovarian reserve.

  • Irregular, absent, or heavy periods. To help identify whether ovulation is occurring.

  • Menopause symptoms. To contextualize hot flashes, night sweats, mood changes, or vaginal dryness.

  • Signs of PCOS. To find the cause of irregular cycles, acne, or excess hair growth.

  • Possible pituitary or hypothalamic conditions. To monitor for low LH, which can indicate disorders in hormone regulation.

  • Fertility treatments. To guide ovulation induction or IVF cycles.

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Not available in all 50 states. Eligibility and provider order required. Lab results alone are not intended to diagnose, treat, or cure any condition. A provider will reach out about critical results and plans include access to 24/7 provider messaging.

Images for illustrative purposes only.

Frequently asked questions

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What causes changes in LH levels?

LH fluctuates naturally with the menstrual cycle, and lifestyle factors and medication can also influence levels.

High LH may suggest menopause or perimenopause, primary ovarian insufficiency (POI), PCOS, thyroid diseases or adrenal gland disorders, and chromosomal disorders such as Turner syndrome. Factors that can raise LH levels include fertility treatments, nonsteroidal anti-inflammatory drugs (NSAIDs), smoking, and stress.

Low LH may suggest hypothalamic amenorrhea, pituitary dysfunction, congenital conditions, like Kallmann syndrome (less common in females), luteal phase defect, and pregnancy (naturally low LH due to high estrogen and progesterone). Factors that can lower LH levels include strenuous exercise, weight loss, glucocorticoids, and birth control pills.

What is the typical reference range for LH in women?

The typical reference range depends on where you are in your cycle and whether or not you’re in menopause:

• Follicular phase. 1.9–12.5 mIU/mL.

• Mid-cycle. 8.7–76.3 mIU/mL.

• Luteal phase. 0.5–16.9 mIU/mL.

• Post-menopause. 10.0–54.7 mIU/mL.

When is the best time to test LH for fertility?

LH changes throughout the menstrual cycle. The best day to capture the level is cycle day 3 for baseline, or mid-cycle if checking for the ovulatory surge.

Do I need to fast before an LH test?

You typically don’t need to fast before an LH test, but you should always check in with your healthcare provider for special instructions.

What’s the difference between an LH blood test and an at-home ovulation kit?

Blood tests measure exact LH levels, while home urine kits detect LH surge qualitatively. Both help confirm ovulation timing, but a blood test is more precise.

Can LH testing confirm menopause?

Persistently elevated LH with low estradiol and high FSH supports a menopause diagnosis.

Does insurance cover LH testing?

Yes, insurance can cover LH testing for infertility, menstrual irregularities, or menopause evaluation. Hers doesn’t require insurance for hormone testing.

What tests are related to this biomarker?

• Follicle-stimulating hormone (FSH)

• Estradiol (E2)

• Anti-Müllerian hormone (AMH)

• Progesterone

• Thyroid function tests

• Prolactin

The information provided here is for informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always talk to a qualified healthcare provider about your specific health concerns.

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Reviewed by Felix Gussone, MD

Published 12/04/2025