What is growth hormone deficiency?

This condition occurs when your pituitary gland, a pea-size structure at the base of the brain, doesn’t make enough growth hormone. This hormone controls development of the body’s bones and organs. Children with untreated growth hormone deficiency (GHD) are shorter than their peers and have other symptoms.

Adults need less growth hormone, but it still plays an important role in:

• Heart function
• Bone health
• Processing protein, carbohydrates and fat
• Memory and concentration

Types and causes of growth hormone deficiency

GHD is classified by when it starts:

• Child-onset GHD is present at birth or starts in childhood. It can be carried into adulthood.
• Adult-onset GHD develops in adulthood.

It’s also classified by cause:

• Congenital GHD is present at birth because of a genetic defect passed down by one or both parents. Subtypes IA, IB, IIB and III are linked to different genetic defects and how they are passed down. 
• Acquired GHD can be present at birth, or it can develop later in childhood or adulthood. This type is caused by damage to the pituitary gland or the hypothalamus, the brain structure that controls the pituitary gland. The cause of the damage may be a head injury, a brain tumor, an infection, or surgery or radiation therapy to treat a tumor or another condition.
• Idiopathic GHD has an unknown cause.

Genetic testing: If your doctor suspects you have inherited GHD, you can discuss whether genetic testing is right for you. Our geneticists and genetic counselor can review your medical and family history in detail.

Who gets growth hormone deficiency?

Incidence: Growth hormone deficiency is relatively rare. About one in 4,000 to 6,000 children have GHD, and it affects about 50,000 U.S. adults.

Sex: GHD, except for one inherited subtype, affects boys and girls equally, though data shows boys are more likely to be diagnosed and treated.

Race/ethnicity: Scientists are not aware of differences across racial or ethnic groups, though data suggests that white people are more likely to be diagnosed and treated.

Risk factors: A family history of GHD or having had brain surgery or radiation therapy to the head can increase risk of GHD.

Symptoms and complications of growth hormone deficiency

With GHD, you may have symptoms such as:

• Fatigue
• Sleep problems
• Bone loss
• Muscle weakness
• Weight gain, especially around the belly
• Thinner skin
• Low motivation

GHD also causes an increase in “bad” cholesterol (LDL) and a decrease in “good” cholesterol (HDL). Blood triglycerides (another type of fat) may rise, potentially damaging blood vessels.

GHD can lead to complications such as increased risk of stroke or heart attack. Some patients have emotional changes, such as feeling depressed or isolated.

Diagnosing growth hormone deficiency

Because GHD is often mistaken for other pituitary conditions, it’s important to be evaluated by experts. At the OHSU Pituitary Center, our specialists have the detailed knowledge needed to give you the correct diagnosis.

Exam: We will start with a physical exam and ask you about your symptoms.

Other tests, called stimulation tests, help us measure GH levels. If your levels don’t reach expected numbers during the test, it could indicate a GH deficiency.

Insulin tolerance test: We inject you with insulin to lower your blood sugar. Low blood sugar sends a message to the pituitary gland to release GH. We take blood samples over a couple of hours to check GH levels. This test produces reliable results, but because it relies on lowering blood sugar, it can result in more discomfort for patients than newer stimulation tests.

Glucagon stimulation test: We inject glucagon into an arm muscle to increase your body’s production of GH. We take blood samples a few times over about three hours to check levels.

Macimorelin stimulation test: In this test, approved by the U.S. Food and Drug Administration in 2017, you take macimorelin (brand name Macrilen) in a drink to stimulate GH production. We check blood samples four times over 90 minutes.

Growth hormone deficiency treatments

Replacing growth hormone to treat GHD involves:

Injection: You inject yourself every day with a small needle. We’ll help you become comfortable with this.

Side effects: When you first start the medication, you may have muscle or joint aches, and mild swelling from fluid retention. They usually improve after we adjust your dose to the right level for you.

Monitoring: We test your levels and adjust your dose as needed, to control side effects and improve your well-being. We’ll make sure you don’t get too much GH, which can lead to muscle or joint pain, headaches and blurry vision.

Effects of treatment: The goal of GH replacement therapy is to improve your health and reverse GHD features, such as belly fat and low bone density. Many patients see significant benefits from GH replacement. They may gain improved bone density, greater ability to exercise and improved well-being.

Learn more

• Isolated growth hormone deficiency, Genetics Home Reference
• Growth Hormone Deficiency, National Organization for Rare Disorders
• GH Deficiency, Pituitary Network Association
• Growth Hormone Deficiency in Adults, Hormone Health Network