Merck Manual

Please confirm that you are not located inside the Russian Federation

honeypot link
Quick Facts

Gigantism and Acromegaly


The Manual's Editorial Staff

Last full review/revision Feb 2021| Content last modified Feb 2021
Click here for the Professional Version
Get the full details
Topic Resources

What are gigantism and acromegaly?

Gigantism and acromegaly are patterns of abnormal growth caused by having too much growth hormone.

In children, too much growth hormone causes gigantism, meaning being gigantic or a giant.

In adults, too much growth hormone causes acromegaly.

  • In gigantism, children grow to be very tall

  • In acromegaly, adults don't grow taller but have deformed bones and skull

  • Other symptoms include weakness, vision problems, and heart problems that can lead to heart failure

  • Doctors treat gigantism and acromegaly with surgery and medicines to lower growth hormone levels

What causes gigantism and acromegaly?

Gigantism and acromegaly are almost always caused by:

  • A noncancerous (benign) tumor on your pituitary gland that makes extra growth hormone

The pituitary gland is a pea-sized bit of tissue at the bottom of your brain. Glands are organs that make and release hormones into your blood. Hormones are chemicals that stimulate other cells or tissues into action. Your pituitary gland makes many different types of hormones, including growth hormone.

The extra growth hormone in your blood causes your bones, muscles, and organs to grow bigger.

Locating the Pituitary Gland

Locating the Pituitary Gland

What are the symptoms of gigantism?

Gigantism is a disease of children. Symptoms include:

  • Extreme growth of long bones, so arms and legs are very long

  • Growing very tall

  • Starting puberty later than normal

  • Sometimes, problems with the development of the genitals

What are the symptoms of acromegaly?

Acromegaly is a disease that usually starts between the ages of 30 and 50. Unlike children's bones, adult's bones can't grow longer. Instead, their bones change shape and deform. Symptoms include:

  • Coarsening, thickened facial features

  • Swollen hands and feet

  • Needing to get larger-sized rings, gloves, hats, and shoes

  • A thick, barrel-shaped ribcage

  • Joint pain

  • Sometimes, weakness in arms and legs

  • In women, irregular periods

  • In men, erectile dysfunction

What problems do gigantism and acromegaly cause?

Untreated gigantism and acromegaly can cause:

People with untreated gigantism and acromegaly have a shorter life expectancy.

How can doctors tell if a person has gigantism or acromegaly?

It's usually easy to see when children are growing too much. But in adults, it may take a long time to notice the abnormal bone growth in acromegaly because it happens little by little.

If doctors suspect gigantism or acromegaly, they:

  • Sometimes, look at photos of you taken over time—these can show physical changes common in acromegaly

  • Do blood tests to measure growth hormone levels

  • Do x-rays of your hands to look for thickened bones or swollen tissue

  • Do CT scan or MRI of the brain to look for a tumor in your pituitary gland

How do doctors treat gigantism and acromegaly?

Doctors treat gigantism and acromegaly using a combination of:

  • Surgery to remove a pituitary gland tumor

  • Radiation therapy

  • Medicine that stops you from producing growth hormone

After surgery or radiation to treat a pituitary gland tumor, you may need to take hormone supplements to replace the ones the pituitary makes.

NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
Click here for the Professional Version
Others also read

Also of Interest

Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID