Melanocyte Stimulating Hormone (MSH)

  • MSH is produced by the pituitary, hypothalamus and skin cells.

  • The pituitary releases MSH in response to increased UV (sun) exposure in the skin.

  • MSH regulates melanin levels in the skin, hair and eyes (pigments and skin tone). It also regulates protection in the skin against UV rays.

  • MSH is produced from the same starting molecule as ACTH (see adrenal insufficiency).

  • MSH has anti-inflammatory properties and can affect the hormone aldosterone (which regulates salt and fluid balance).

Further reading at You & Your Hormones here.

MSH excesses (too much)

Too much MSH can lead to hyperpigmentation in the skin. This is often linked to conditions where there is too much ACTH (see information on adrenal insufficiency and HPA axis).

MSH deficiency (too little)

Too little MSH (where there has been damage to the pituitary) can lead to reduced skin tone, melanin and reduced natural protection against UV rays.

It can also cause problems with sleep, inflammation, perception of pain, reduction in anti-diuretic hormone (see posterior pituitary), increased appetite and obesity.

Testing for MSH levels

MSH levels in the blood can be measured in a blood test, however it is not commonly tested for.

Hormone replacement for MSH

There isn’t a routine hormone replacement medication for MSH in pituitary patients, talk to your endocrinologist about this if you are concerned.

Staying safe in the sun

It’s important for everyone to wear sun protection, however if you have ACTH deficiency (secondary adrenal insufficiency) be extra aware that your skin’s natural protection may not be as high.