Luteinizing hormone (LH) is a hormone produced by the pituitary gland in the brain. It is a part of the endocrine system and plays an important role in the reproductive system of both males and females.
LH is in the male physiology probably most known for stimulating the production of testosterone in the testes, thereby regulating the production of sperm and the development of male sexual characteristics.
Normal LH levels indicate that hormonal pathways and signaling mechanisms between testosterone and LH are in balance, which is necessary for testicular function and fertility.
Since LH stimulates the production of testosterone in the testes, measuring LH in men is foremost of interest when investigating testicular dysfunction (lack of testosterone effect).
By measuring LH together with testosterone, one can receive valuable information on whether or not the dysfunction is deriving from within the testicles directly (also known as primary hypogonadism) or from the hypothalamus and pituitary gland in the brain, hormonally controlling the testicles (known as secondary hypogonadism). This comes especially handy in fertility investigations.
High levels of LH indicate that the testicles and testosterone production aren’t fully functioning as they should. This is because high levels suggest that the hypothalamus and the pituitary gland, regulating the function of the testicles, are trying to compensate for a problem with the reproductive system.
Important note: It is important to interpret LH levels in the context of other hormone levels and symptoms to definitely determine the underlying cause of elevated LH levels.
Low levels of LH generally indicate that the body is not producing enough LH, which in turn can disrupt the reproductive system. This suggests that the affected parts of the body are the ones responsible for the LH production.
If the hypothalamus, responsible for the measuring and evaluation of all hormones in our body, is not functioning properly, the signaling for increased LH will not function properly. If hypothalamus is well functioning, but the pituitary gland receiving the orders of increased LH production needs is not functioning properly, the LH production won’t increase.
Thus meaning that issues with the hypothalamus and the pituitary gland can be the underlying cause of low LH. Other causes may be chronic stress, testosterone treatment and the use of anabolic steroids.