Growth Hormone Deficiency

What growth hormone does

Growth hormone (GH) is released by the pituitary gland in pulses, mostly during sleep. It acts mainly through IGF-1 (insulin-like growth factor 1), made by the liver, to stimulate bone growth in children. Throughout life, it also helps maintain muscle and bone mass, controls fat distribution and supports metabolism.

Causes

Present from birth (congenital)

• Genetic changes affecting GH production or pituitary development
• Structural brain differences, such as septo-optic dysplasia or midline defects (cleft lip and palate)
• Pituitary underdevelopment, often with other hormone deficiencies

Acquired later

• Pituitary or hypothalamic tumors, including craniopharyngioma in children and pituitary adenomas in adults
• Surgery or radiation to the brain or pituitary, including cranial radiation for childhood cancer
• Traumatic brain injury and bleeding in the brain
• Infections and inflammatory conditions of the pituitary
• Idiopathic: no cause found, common in children

GHD may be isolated or part of hypopituitarism, where other pituitary hormones (thyroid, adrenal, sex hormones) are also low.

Symptoms

In babies

• Low blood sugar
• Prolonged newborn jaundice
• A very small penis in boys (micropenis)
• Normal birth size, as growth before birth does not depend on GH

In children

• Slow growth: height falling away from the normal curve, usually noticed after age 2 to 3
• Short stature for age and family
• Chubby, younger-looking appearance and face
• Delayed tooth development
• Delayed puberty
• Normal intelligence

In adults

• Tiredness and low energy
• Decreased muscle mass and strength
• Increased fat, especially around the waist
• Reduced bone density and higher fracture risk
• Raised cholesterol
• Low mood, anxiety and reduced quality of life
• Thin, dry skin

Other causes of short stature to consider

Most short children do not have GHD. Common alternatives include familial short stature (short parents), constitutional delay of growth and puberty ("late bloomers"), poor nutrition, chronic illness such as celiac disease or Crohn's disease, hypothyroidism, Turner syndrome in girls, and other genetic conditions.

Diagnosis

• Growth assessment: accurate height measurements over time, plotted on growth charts, and comparison with parents' heights.
• Blood tests: IGF-1 and IGFBP-3 levels, thyroid function and other pituitary hormones, and tests for celiac disease and other chronic illness.
• Bone age X-ray: an X-ray of the left hand and wrist shows skeletal maturity. In GHD, bone age is usually delayed.
• Growth hormone stimulation tests: medicines are given to trigger GH release, and blood levels are measured over a few hours. Children usually need two tests, because healthy children can fail one test.
• MRI of the brain and pituitary to look for structural causes or tumors.
• Genetic tests in selected children.

Adults are usually tested only when they have a known pituitary or brain condition, with stimulation tests such as the macimorelin or glucagon test.

Treatment

• Growth hormone (somatropin) injections: given under the skin, traditionally daily at bedtime. Long-acting weekly formulations are now also available for children and adults.
• Monitoring: height every 3 to 6 months in children, IGF-1 levels to adjust the dose, and checks of thyroid function, blood sugar and spine curvature.
• Treating other hormone deficiencies when present.
• Duration in children: until growth slows near final height, after which adults with persistent GHD may continue at a lower dose.

Possible side effects include headache, joint pain, swelling, and rarely raised pressure in the skull (idiopathic intracranial hypertension), slipped capital femoral epiphysis (hip problem) and worsening of scoliosis. Families should report limping, hip or knee pain, and persistent headaches.

Outlook

Children with GHD who start treatment early often reach a normal or near-normal adult height. The earlier treatment begins, the better the result. Adults treated for GHD often notice improved energy, body composition, bone density and quality of life over months.

Frequently asked questions

What are the signs of growth hormone deficiency in children?

The main sign is slow growth, with the child's height falling below the expected curve on growth charts, usually after age 2 to 3. Other signs include a younger-looking face, a chubby build, delayed tooth development and delayed puberty. Babies may have low blood sugar or a small penis.

What causes growth hormone deficiency?

It can be present from birth because of genetic changes or brain development differences, or acquired later from pituitary or brain tumors, surgery, radiation, head injury or infection. In many children, no cause is found. It can occur alone or with other pituitary hormone deficiencies.

How is growth hormone deficiency diagnosed?

Doctors review growth charts, check IGF-1 levels and a bone age X-ray, and then perform growth hormone stimulation tests, which measure how much GH the pituitary releases after medicine. An MRI of the pituitary looks for a cause.

Can adults have growth hormone deficiency?

Yes. Adult GHD usually results from pituitary tumors, surgery, radiation or head injury, or continues from childhood. It causes tiredness, reduced muscle, increased belly fat, weaker bones and low mood. Growth hormone treatment can improve these symptoms.