Luteinising hormone (LH) is released from the pituitary gland in the brain. It is responsible for controlling ovulation, oestrogen production and maintenance of a pregnancy in the female, and stimulates sperm production and production of testosterone in the male testes.
The level of LH in blood can be measured to investigate menstrual cycle disorders and infertility. Normal results vary between laboratories, but a representative range is:-
|Before puberty||1 to 3.4 IU/L.|
|Male||2 to 9 IU/L.|
|Fertile female||2 to 20 IU/L.|
|At time of ovulation in females||10 to 50 IU/L.|
|After menopause||30 to 200 IU/L.|
Low levels may indicate infertility or hypogonadism (ovary or testicle not functioning properly to produce sex hormones). High levels may indicate that the test was taken at the time of ovulation, the child may be having a premature puberty, or the Stein-Leventhal syndrome.