Luteinising Hormone

Luteinising hormone, commonly known as LH, is a chemical messenger produced by the pituitary gland, a small, pea-sized structure at the base of your brain. It is central to reproductive health for both men and women, acting as a key signal in the complex hormonal conversation that governs fertility and sexual function. In women, LH is best known for triggering ovulation, the moment each month when a mature egg is released from the ovary, making conception possible. In men, LH sends a signal to specialised cells in the testes to produce testosterone, the hormone responsible for many aspects of male health.

Think of LH as a conductor in an orchestra: it does not play the instruments itself, but without its direction, the other hormones cannot perform their parts in harmony. Your pituitary gland carefully adjusts how much LH it releases based on feedback from your sex hormones, maintaining a delicate balance throughout your cycle or daily rhythm. An LH level within the reference range is best read alongside your sex hormone results. A number of factors can influence your LH levels, including age, stress, significant changes in body weight, and intense physical exercise.

In women, LH naturally fluctuates throughout the menstrual cycle, peaking sharply just before ovulation, so the timing of your blood test matters. Certain medications, including hormonal contraceptives, can also affect your results. If your LH level falls outside the expected range, it is well worth having a conversation with your GP, who can look at it alongside your other hormone results and help you understand what it means for you personally.