Leutinising Hormone (LH) Test

The Luteinising Hormone (LH) test is a blood test used to measure the level of luteinising hormone in the body. LH is secreted by the pituitary gland, a small gland found at the base of the brain. This test is also known as the LH blood test, serum LH test, or lutropin test. 

LH helps control the reproductive system and supports normal sexual and reproductive functions in both men and women. 

• In women, it helps release eggs during ovulation (the release of a mature egg from the ovary during the menstrual cycle) and supports the menstrual cycle. 
• In men, it helps produce testosterone and sperm. 
• In children, LH helps start the physical changes that happen during puberty, such as: 
• Boys: Helps the testicles produce testosterone, which supports body hair growth, voice changes, and sperm synthesis. 
• Girls: Helps the ovaries produce oestrogen, which is important for breast development, body hair growth, and the start of menstruation.

The LH test helps doctors evaluate reproductive and hormonal health. In women, it helps assess ovulation, menstrual irregularities, fertility issues, and conditions such as polycystic ovary syndrome (PCOS) or menopause. In men, it helps evaluate testosterone production and potential causes of infertility or delayed puberty. 

Hence, the LH test mainly focuses on the pituitary gland and the reproductive organs, including the ovaries in women and testes in men.

An LH blood test may be advised if a person exhibits symptoms of hormonal imbalance, fertility problems, or reproductive health issues. Doctors use this test to determine how well the pituitary gland and reproductive organs are working. The test may be recommended by doctors in the following situations: 

• In Women

An LH test may be recommended for the following reasons: 

• Menstruation is irregular or has stopped 
• Not getting pregnant despite trying for 12 months
• Have ovary-related medical conditions such as PCOS (symptoms such as irregular periods, oily skin, excessive hair growth, dark skin patches, weight gain, etc.)
• Have symptoms of menopause (irregular periods, hot flashes, difficulty in sleeping, vaginal dryness, mood changes, etc.) 

Note: Changes in the level of the LH hormone during menopause or perimenopause (periods before menopause) are quite natural. But it should be confirmed through an LH test. 

• In Men

LH test may be recommended for the following reasons: 

• Loss of interest in sexual activities or reduced sex drive 
• Low sperm count or testosterone levels 
• Unable to fertilise even after trying continuously for 12 months 
• Decrease in muscle strength and body hair growth 
• Have any testicle-related medical condition (as a routine checkup) 

• In Both Women and Men

LH test may be recommended for the following reasons: 

• To diagnose pituitary gland and hypothalamus-related disorders 
• Experiencing fatigue or weakness 
• Sudden weight reduction or change 
• Reduced hunger or appetite

• In Children and Teens

LH test may be recommended for the following reasons: 

• Early puberty: Before 8 years of age in girls and 9 years in boys 
• Delayed puberty: Not showing any signs by 13 years of age in girls and 14 years in boys

The frequency for performing an LH test depends on sex, cause, and age. The following table might help you better understand when to get an LH test. 

Note: The frequency of LH testing may differ according to an individual's symptoms, medical history, age, and overall health status. Always seek the opinion of a qualified doctor when it comes to testing and interpretation of results. 

An LH test may help detect the following: 

In women 

Changes in LH level can help detect the following: 

• Tracking ovulation: Helps identify the release of an egg during the menstrual cycle. 
• Causes of infertility: Absence or difficulty releasing eggs regularly, making pregnancy harder. This could be due to: 
• Polycystic ovary syndrome (PCOS): A hormonal disorder that can cause irregular periods and fertility issues.
• Primary ovarian insufficiency (POI): A condition where the ovaries stop functioning properly before age 40. 
• Turner syndrome: A genetic condition in females that affects ovarian development and puberty.
• Thyroid disease: An imbalance in thyroid hormone that can affect menstrual cycles and fertility. 
• Adrenal gland disorders: Conditions affecting adrenal hormones that may interfere with reproduction and ovulation. 
• Menopause or perimenopause: Natural decline in reproductive hormones causing menstrual and body changes.

In men 

The changes in LH level help detect the following: 

• Infertility: Difficulty having a child due to problems with hormones or sperm. 
• Testicular disorders or damage: Conditions affecting the normal function of the testicles. 
• Germ cell tumour: A tumour that begins in the cells that convert to sperm. 
• Mumps: An infection that can cause inflammation of the testicles and cause infertility if left untreated.
• Klinefelter syndrome: A genetic condition in men that can affect puberty, cause reduced testosterone levels, and cause infertility.

In both women and men 

The changes in LH level can help detect some common conditions, such as the following: 

• Pituitary gland disorders: Problems in the pituitary gland affecting hormone production. 
• Hypothalamus disorders: Conditions affecting the brain region that controls hormone release. 
• Autoimmune diseases: Certain autoimmune conditions (diabetes, psoriasis, Inflammatory bowel disease, etc.) may affect reproductive function and hormone levels. 
• Changes can also occur as a side effect of chemotherapy or radiation therapy.

In teens (with no signs of puberty) 

Changes in LH levels help detect the causes of delayed puberty. These include the following: 

• Certain genetic disorders: Such as Kallman syndrome, Turner syndrome (in girls), and Klinefelter syndrome (in boys) 
• Tumour: In the brain or pituitary gland 
• Poor nutrition: Resulting from eating disorders or long-term health issues 
• Chemotherapy or radiation therapy 
• Autoimmune disorders

In children (with early signs of puberty)

The changes in LH may help detect the causes of early puberty. These include the following: 

• Brain problems: Injuries, tumours, or brain infection (meningitis or encephalitis) 
• Variations in levels of oestrogen or testosterone hormones: Caused by disorders of the ovaries, testicles, or adrenal glands that produce more of these hormones 
• Certain medications: Medicines that contain sex hormones (cause early puberty)

What to Expect Before the LH Test

No fasting is required for a standalone LH test. You can eat and drink normally. However, if it is part of a broader package that includes fasting tests, your doctor may advise fasting for 8-12 hours. Avoid strenuous exercise for 24 hours before the test, as intense physical activity can temporarily raise LH levels and affect interpretation. Always inform your doctor about any ongoing medications.

What to Expect During the Blood Collection

A phlebotomist cleans the skin with an antiseptic, then places an elastic band around your upper arm to make the veins easier to access. A small needle is inserted into the vein; you may feel a brief pinch. Blood is collected into a labelled tube in under a minute.

What to Expect After the LH Test

A small cotton swab and bandage are placed over the site to stop any minor bleeding. You can return to normal activities immediately. Minor bruising is normal and disappears quickly. If dizzy, sit and rest for a few minutes.

The LH test only measures the level of a single parameter: 

• Luteinising Hormone (LH)

LH is a hormone produced by the pituitary gland that plays an important role in reproduction. In women, it helps trigger ovulation and controls the menstrual cycle, while in men, it supports testosterone production, which is essential for sperm production.

The table below shows the LH normal range: 

Note: Normal LH levels vary according to age, gender, menstrual cycle phase, and laboratory procedures. Test results should always be interpreted by a qualified doctor along with symptoms and medical history.

The table below says what the variation from the normal LH range in females and males may indicate: 

Note: LH values must always be evaluated in conjunction with age, gender, symptoms, and other hormone testing (such as oestrogen or testosterone). The results should always be interpreted by a qualified doctor. 

The LH test is generally safe and useful as it is a simple blood test, but like all medical tests, it has certain risks and limitations. 

Risks 

• Mild discomfort or pain (experienced during sample collection). 
• Bruising or minor bleeding at the injection site (after sample). 

However, these might resolve quickly. 

Limitations 

• LH levels naturally change with age, sex, and the menstrual cycle. 
• The test cannot detect a problem on its own; it is typically used together with other hormonal tests.

LH is usually interpreted along with other tests to better understand hormonal and reproductive health. These include: 

• Follicle-stimulating hormone (FSH) test 
• Oestrogen or oestradiol test 
• Prolactin test 
• Testosterone test 
• Progesterone test 
• Pelvic ultrasound or testicular ultrasound 
• Thyroid function tests 
• Ovulation tests or fertility assessments 
• Semen analysis (in men) 
• Genetic testing