LH Luteinizing hormone

LH is an abbreviation for Lutropin, or luteinizing hormone (LH), is a hormone produced by the pituitary gland in the brain. In women, LH plays an important role in the menstrual cycle by triggering ovulation. In men, LH stimulates the production of testosterone in the testicles, which is crucial for sperm production and male fertility.

LH is analyzed when investigating fertility problems, irregular menstruation, suspected menopause or hormonal imbalances. In men, LH is measured when low testosterone production or hypogonadism is suspected. LH levels provide information about the function of the pituitary gland and gonads.

Normal levels vary depending on gender, age, and phase of the menstrual cycle. For women of childbearing age, LH levels are normally between 2–12 IU/L in the follicular phase and can rise to 20–80 IU/L at ovulation. In men, LH is usually between 1.5–9.3 IU/L.

High LH levels in women may indicate ovulation, menopause, or conditions such as PCOS. In men, high LH may indicate that the testicles are not responding normally, which may be due to testicular damage or primary hypogonadism. During menopause, LH naturally rises due to decreased hormone production in the ovaries.

You can submit the sample at any time. However, for women, it is important to indicate which day of the menstrual cycle the test is performed, which you fill in on the health declaration. Many recommend taking the sample on day 3 or when ovulation is suspected (day 12–14), but this varies depending on the purpose of the sample. For men, the sample can be taken at any time of the day, as LH levels are more stable.

LH (luteinizing hormone) and FSH (follicle-stimulating hormone) work together to regulate the menstrual cycle in women and testosterone production in men. A balance between LH and FSH is important for normal hormone function. An elevated LH/FSH ratio in women may indicate conditions such as PCOS (polycystic ovary syndrome), while low levels of either hormone may indicate pituitary insufficiency.

Ovulation tests measure the amount of LH in the urine, as LH increases sharply (the LH peak) 24–36 hours before ovulation. A positive test indicates that ovulation is likely to occur within the next 24 hours. This information is especially important for women who want to optimize their chances of getting pregnant by pinpointing their most fertile period.

Women with PCOS often have elevated LH relative to FSH, sometimes with an LH/FSH ratio above 2:1. This can lead to irregular ovulation or no ovulation, which affects fertility. High LH also contributes to increased production of androgens (male hormones), which can cause symptoms such as acne, increased body hair and weight gain. A blood test for LH along with other hormones is important in the investigation of PCOS.