Luteinising Hormone – Class 12 | Chapter – 3 | Biology Short Notes Series PDF

Luteinising Hormone: Luteinising hormone is a gonadotrophic hormone produced and released by cells in the anterior pituitary gland. It is crucial in regulating the function of the testes in men and ovaries in women.

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In men, luteinising hormone stimulates Leydig cells in the testes to produce testosterone, which acts locally to support sperm production. Testosterone also exerts effects all around the body to generate male characteristics such as increased muscle mass, enlargement of the larynx to generate a deep voice, and the growth of facial and body hair.

In women, luteinising hormone carries out different roles in the two halves of the menstrual cycle. In weeks one to two of the cycle, luteinising hormone is required to stimulate the ovarian follicles in the ovary to produce the female sex hormone, oestradiol. Around day 14 of the cycle, a surge in luteinising hormone levels causes the ovarian follicle to rupture and release a mature oocyte (egg) from the ovary, a process called ovulation. 

Importance of Luteinising Hormone

  • In women, LH helps control the menstrual cycle. It also triggers the release of an egg from the ovary. This is known as ovulation. LH levels quickly rise just before ovulation.
  • In men, LH causes the testicles to make testosterone, which is important for producing sperm. Normally, LH levels in men do not change very much.
  • In children, LH levels are usually low in early childhood, and begin to rise a couple of years before the start of puberty. In girls, LH helps signal the ovaries to make estrogen. In boys, it helps signal the testes to make testosterone.

Disorders of the Luteinising hormone

  • High levels of LH in a woman may be a sign of primary ovarian failure.
  • Low levels of LH in a woman may be a sign of secondary ovarian failure.
  • High levels of LH in men are a sign of a problem with the testicles.
  • Low levels of LH result in disorder with the pituitary gland or hypothalamus.

Need of Luteinising hormone Test

In women, these tests are most often used to:

  • Help find the cause of infertility
  • Find out when ovulation occurs, this is the time when you are most likely to get pregnant.
  • Find the reason for irregular or stopped menstrual periods.
  • Confirm the start of menopause, or perimenopause. 
  • If a women is unable to get pregnant after 12 months of trying.

In men, these tests are most often used to:

  • Help find the cause of infertility
  • Find the reason for a low sperm count
  • Find the reason for low sex drive

In children, these tests are most often used to help diagnose early or delayed puberty.

  • Puberty is considered early if it starts before age 9 in girls and before age 10 in boys.
  • Puberty is considered delayed if hasn’t started by age 13 in girls and by age 14 in boys.

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By Team Learning Mantras