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Luteinizing Hormone (LH) Blood Test: A Key Marker for Reproductive and Hormonal Health

The Luteinizing Hormone (LH) Blood Test, included in the PlexusDx Women’s Health & Wellness Blood Test, measures the level of LH in the bloodstream. LH is a pituitary hormone that plays an essential role in regulating the menstrual cycle, fertility, and overall reproductive health. In women, LH works in tandem with follicle-stimulating hormone (FSH) to regulate estradiol production, trigger ovulation, and support early pregnancy. Because LH levels fluctuate naturally across the menstrual cycle and rise after menopause, this biomarker offers important insight into hormonal balance, fertility potential, and pituitary function.

What is LH?

LH is produced by the pituitary gland, located at the base of the brain. It communicates with the ovaries via the hypothalamic-pituitary-ovarian (HPO) axis, coordinating reproductive and hormonal activity. Key roles of LH in women include:

  • Regulating Estradiol: Works with FSH to stimulate ovarian follicles to produce estradiol (a form of estrogen).
  • Triggering Ovulation: A mid-cycle surge in LH triggers the release of a mature egg from the ovary, a critical step for conception.
  • Supporting Progesterone: After ovulation, LH stimulates the corpus luteum to produce progesterone, which prepares the uterine lining for pregnancy.
  • Postmenopause: As ovarian function declines, LH levels rise significantly, making it a marker of menopausal transition.

The Role of LH in the Body

Although LH is primarily known for its role in ovulation, it influences a broad range of reproductive and hormonal processes:

  • Menstrual Cycle Regulation: Ensures that egg release and hormone production remain coordinated for fertility.
  • Fertility Potential: Provides a snapshot of ovulation timing and ovarian health.
  • Hormone Balance: Works closely with FSH, estradiol, and progesterone to maintain reproductive hormone equilibrium.
  • Pituitary Health: Abnormal LH levels can signal pituitary dysfunction, which impacts multiple hormone systems.

Why Measure LH Levels?

LH testing is frequently ordered to assess reproductive and hormonal health. Reasons for measuring LH include:

  • Fertility Evaluation: Helps identify whether ovulation is occurring and provides insights into reproductive timing.
  • Irregular or Missed Periods: Detects hormone imbalances contributing to menstrual irregularities.
  • Infertility: Evaluates ovarian function alongside FSH, estradiol, and progesterone.
  • Menopausal Transition: Elevated LH levels help confirm perimenopause or menopause.
  • Low Testosterone or Reduced Sex Drive: In men, LH testing helps assess testicular function; in women, it may reveal imbalances affecting libido.
  • Pituitary Disorders: Abnormal levels can indicate pituitary gland dysfunction that impacts hormone regulation.

Specimen Collection Method

The PlexusDx Women’s Health & Wellness Blood Test uses a simple at-home dried blood spot (DBS) collection with an ADX card. This method requires only a finger prick, making it convenient, non-invasive, and accurate. Once the sample is collected, it can be mailed directly to the lab for analysis without the need for a clinic visit.

Reference Ranges for LH

LH levels vary depending on age, menstrual cycle phase, and reproductive status. Typical laboratory ranges for women are:

Standard Laboratory Ranges (Women)

  • Follicular phase: 1.9 – 12.5 mIU/mL
  • Mid-cycle (ovulation surge): 8.7 – 76.3 mIU/mL
  • Luteal phase: 0.5 – 16.9 mIU/mL
  • Postmenopause: 15 – 62 mIU/mL

Functional and Optimal Ranges

Functional medicine often uses narrower, cycle-specific ranges to evaluate subtle imbalances:

  • Optimal follicular phase: 2 – 8 mIU/mL
  • Optimal luteal phase: 1 – 8 mIU/mL

Maintaining LH within these optimal ranges supports regular ovulation, balanced hormone production, and reproductive health.

High LH Levels

Elevated LH may indicate a number of health conditions. In women, high LH may be linked to:

  • Polycystic ovary syndrome (PCOS)
  • Ovarian insufficiency or menopause
  • Pituitary disorders producing excessive LH

Symptoms may include irregular cycles, infertility, hot flashes, or androgen-related changes such as acne or excess hair growth.

Low LH Levels

Low LH can indicate insufficient pituitary or hypothalamic function, which reduces ovarian stimulation. Causes and symptoms may include:

  • Causes: Hypothalamic amenorrhea, pituitary disorders, extreme stress, over-exercising, or low body weight.
  • Symptoms: Missed or irregular periods, infertility, fatigue, low libido, or hormonal imbalance.

Factors That Influence LH Levels

Several factors can impact LH results:

  • Age: LH levels rise significantly after menopause.
  • Cycle Phase: Levels naturally fluctuate throughout the menstrual cycle, peaking during ovulation.
  • Stress: Chronic stress can disrupt LH release and ovulation.
  • Body Weight: Low body fat or obesity may alter LH production and balance.
  • Medical Conditions: PCOS, pituitary dysfunction, or thyroid disorders can influence LH levels.

How to Support Healthy LH and Reproductive Function

Maintaining optimal LH and reproductive health involves lifestyle and medical strategies:

  • Balanced Nutrition: Adequate intake of protein, healthy fats, and micronutrients like zinc and vitamin D supports reproductive hormones.
  • Stress Management: Practices such as meditation, yoga, and restorative activities help normalize hormone patterns.
  • Healthy Weight: Maintaining an optimal BMI supports cycle regularity and hormone balance.
  • Consistent Sleep: Restful sleep stabilizes the hypothalamic-pituitary-ovarian axis.
  • Medical Guidance: For irregular cycles or fertility issues, healthcare providers may recommend hormone therapy, ovulation induction, or further testing.

LH and Whole-Body Health

While LH is primarily recognized for its role in ovulation and reproduction, its significance extends beyond fertility. Balanced LH levels are important for menstrual cycle regulation, hormonal harmony, and overall vitality. Disruptions in LH may explain infertility, irregular cycles, or menopausal symptoms, while also signaling broader hormonal or pituitary imbalances.

Why Choose PlexusDx?

The PlexusDx Women’s Health & Wellness Blood Test offers a comprehensive view of hormone health, including LH, through convenient at-home dried blood spot testing. With simple sample collection and lab-accurate results, you gain the insights needed to understand reproductive health, hormone balance, and overall wellness without leaving home.

Key Takeaways

  • LH is a pituitary hormone essential for estradiol regulation, ovulation, and progesterone support.
  • Levels fluctuate across the menstrual cycle, peak during ovulation, and rise after menopause.
  • High LH may indicate PCOS, ovarian insufficiency, or menopause; low LH may reflect pituitary or hypothalamic dysfunction.
  • Testing LH provides critical insights into fertility, menstrual health, and hormonal balance.
  • The PlexusDx at-home dried blood spot test makes it simple to measure LH as part of a complete women’s wellness panel.

By testing LH levels with the PlexusDx Women’s Health & Wellness Blood Test, women gain essential information about their reproductive health, fertility potential, and hormonal balance—empowering proactive steps toward wellness and healthy aging.