Luteinizing hormone, or LH, is produced in the pituitary gland. In women, it helps regulate the menstrual cycle and egg production. The LH level in a woman's body varies with each phase of the menstrual cycle. For example, it increases just prior to ovulation (egg release). In men, LH stimulates the production of testosterone. LH levels can be low for a number of reasons, so an LH test is done to determine the cause.
Causes of low LH include problems with the pituitary gland, the hypothalamus, the gonads, progesterone deficiency or testosterone insufficiency.
Pituitary Gland Problems
If there are problems with the pituitary gland, there will be a deficiency in LH. For example, hypopituitarism is an underactive pituitary gland which can result in a deficiency in one or more of the gland's hormones, such as LH. According to the Merck Manual, hypopituitarism can be caused by certain inflammatory diseases, a pituitary gland tumour or insufficient blood supply to the pituitary gland. Symptoms may include short height, infertility, intolerance to cold, fatigue and an inability to produce breast milk.
The hypothalamus is a section of the brain that produces hormones that control body temperature, hunger, moods, the release of hormones from the pituitary gland, sex drive, sleep and thirst. Hypothalamic dysfunction occurs when there is a problem with the hypothalamus and that area of the brain. Causes of hypothalamic dysfunction include anorexia, bleeding, bulimia, tumours, head trauma, malnutrition and many others. According to Medline Plus, men may also experience Kallman syndrome, which can cause a lowered function of sexual hormones and the inability to smell.
Women with low LH may experience problems with their progesterone levels. Progesterone is a steroid found in women that is responsible for the changes in the endometrium in the latter half of the menstrual cycle. According to Natural Hormones, progesterone is produced by cells in the ovaries called granulosa cells. When a woman is deficient is progesterone, it can cause infertility, early miscarriage, carbohydrate cravings, irregular periods, ovarian cysts, menstrual cramps, bloating, water retention and lower body temperature
Low LH in men can cause problems with their testosterone levels. Testosterone is a steroid and is the primary male sex hormone responsible for the onset of puberty. According to 4-Men, low testosterone levels can result in erectile dysfunction. Additionally, men can experience changes in mood, emotions, a decrease in body mass and strength, as well as an increase in body fat.