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Basically, LH stands for luteinizing hormone and it is produced by the pituitary gland. In women, the LH is responsible for releasing an egg into the fallopian tube. In men, the LH is responsible for the production of testosterone.
Your doctor might order blood tests to measure luteinizing hormone levels in several circumstances:
• Infertility issues or difficulty conceiving a child
• Irregular menstrual period particularly in teen girls
• To evaluate pituitary function, diagnose pituitary disorders or diseases involving the ovaries or testes
• To determine or confirm the onset of menopause
• Precocious or late onset of puberty
Blood tests for LH levels in women usually also include FSH (follicle stimulating hormone).
How LH Works
Your menstrual cycle consists of three phases. Phase one, the follicular phase, begins on the first full day of menstrual bleeding. Phase two, is the ovulatory phase and immediately follows the end of a woman’s period. Phase three is called the luteal phase and follows ovulation.
In preparation for phase two, the pituitary gland releases LH and FSH. The follicle stimulating hormone is responsible for the growth and ripening of an egg inside a follicle (one of many tiny sacs that carry a developing egg).
Luteinizing hormone stimulates the follicle to generate and secrete estrogen. Increased levels in estrogen (among other things) cause the lining of uterus to fill with nutrients and blood, preparing to receive the mature egg.
When the amount estrogen reaches the appropriate amount, a surge of LH is released from the pituitary gland and within 24 to 36 hours the follicle will burst and release a ripened egg into the Fallopian tube.
The day prior to ovulation and the day of ovulation are the two days a woman is most likely to conceive.
Preparing for the Test
To make sure that your doctor receives the most accurate test results possible, you may be instructed to discontinue using certain medications including birth control pills, which contain estrogen or progesterone or both, for up to four weeks before having a LH screening.