What is S-LH?
Last updated: 30 June 2026
Reviewed by: Elfcare quality team
LH (Luteinizing Hormone) is produced by the pituitary gland in your brain and travels through the blood to trigger key reproductive functions. It is one of the most direct measures of how well your brain and reproductive organs are communicating, and plays a central role in timing the reproductive cycle.
The role of LH in the body
LH triggers the final stages of hormone production and release.
In women, LH is the ovulation trigger. A sharp mid-cycle spike signals the ovary to release a mature egg. After ovulation, it helps convert the empty follicle into the corpus luteum, which produces progesterone to support a potential pregnancy.
In men, LH acts on the Leydig cells in the testes, prompting them to produce testosterone.
Monitoring LH tells us whether the brain is sending strong enough signals at the right time to support reproductive and metabolic function.
Why test LH?
LH can help narrow down the fertile window during a menstrual cycle, and can also explain why other hormones, like testosterone or progesterone, might be low. Testing it lets you see whether your brain is struggling to get a response from the ovaries or testes. This aids in identifying issues like overtraining, chronic stress, or the transition into menopause.
You should be extra attentive to this marker if you:
Are tracking ovulation for family planning.
Are investigating irregular menstrual cycles or a lack of periods.
Are a man with low testosterone and wants to see if the issue originates in the brain or the testes.
Suspect you may be entering perimenopause.
High LH: what does it mean?
A high result typically means the brain is sending stronger signals because it isn't getting enough feedback from the target organs.
Elevated levels may indicate:
Menopause or perimenopause: As ovarian function declines, the brain pumps out high levels of LH and FSH to try and force a response.
PCOS (polycystic ovary syndrome): In many women with PCOS, LH levels are chronically high relative to FSH, which can interfere with regular ovulation.
Primary testicular failure: In men, high LH combined with low testosterone suggests the brain is doing its job, but the testes are unable to produce enough hormone.
The ovulatory surge: In a healthy, cycling woman, a brief, very high LH result is perfectly normal and indicates that ovulation is about to occur.
Low LH: what does it mean?
A low LH result suggests that the signalling centre in the brain is suppressed or underactive.
Common reasons for low levels include:
Pituitary or hypothalamic suppression: High stress, extreme weight loss, malnutrition, or excessive endurance exercise can cause the brain to reduce LH output to conserve energy.
Hormone replacement therapy: Taking external hormones, such as birth control or testosterone, signals to the brain that it doesn't need to produce its own LH, leading to very low levels.
Practical steps for LH balance
You can help maintain LH signalling by managing the lifestyle factors that affect this part of the brain's hormonal output.
Manage energy availability: Ensure you are eating enough to support your activity level. The brain will only prioritise LH signalling if it perceives the body has enough energy in reserve.
Prioritize sleep consistency: LH is released in pulses, often peaking during sleep. Irregular sleep patterns can disrupt these delicate timing signals.
Reduce chronic stress: High cortisol over extended periods can inhibit the hypothalamus, the part of the brain responsible for telling the pituitary to release LH.
Support with zinc: Zinc plays a well-established role in supporting healthy reproductive hormone production.
Disclaimer: These results should always be discussed with a healthcare professional. This guide is for informational purposes and is not medical advice.
Testing with Elfcare
S-LH is included in Elfcare’s blood test package and in our full body health check. We analyse your LH alongside FSH, estradiol, and testosterone to determine whether a hormonal imbalance originates in the brain or the reproductive organs.
Understanding your LH levels is a key step in proactive health. Elfcare’s tests provide the data you need to act before imbalances affect your daily life.
Summary
LH is the signal that triggers ovulation in women and testosterone production in men.
High levels often point to menopause, perimenopause, or a reproductive system that is struggling to respond to the brain's signals.
Low levels are frequently caused by high stress, overtraining, malnutrition, or external hormone use.
Mastering your LH data allows you to synchronize your lifestyle with your brain’s signaling, supporting more informed decisions about fertility and hormonal health.
Last updated: 30 June 2026
Reviewed by: Elfcare quality team
