Growth hormone therapy is a treatment that uses lab-made (synthetic) growth hormone, identical to the hormone your body produces naturally, to treat children and adults whose bodies don’t make enough on their own. The synthetic version is injected under the skin, typically once daily at bedtime, and works by stimulating the same growth and metabolic pathways that natural growth hormone controls. It’s been used since the mid-1980s and is now prescribed for a range of conditions beyond simple growth hormone deficiency.
How Growth Hormone Works in the Body
Your pituitary gland, a pea-sized structure at the base of your brain, releases growth hormone in pulses throughout the day, with the largest bursts during deep sleep. This hormone doesn’t just make bones grow longer in childhood. It plays a central role in metabolism throughout your entire life, influencing how your body builds muscle, breaks down fat, and maintains bone density.
Growth hormone does much of its work indirectly. After the pituitary releases it, the hormone travels to the liver and signals it to produce another hormone called IGF-1 (insulin-like growth factor 1). IGF-1 then circulates through the body and drives the actual tissue growth, bone lengthening, and cell repair. This two-step relay is why doctors monitor IGF-1 levels in the blood to gauge whether therapy is working correctly. Growth hormone also has direct effects on fat and muscle tissue and plays a role in regulating blood sugar by influencing how cells respond to insulin.
Conditions Treated in Children
Growth hormone therapy is approved in the U.S. for several pediatric conditions. The most straightforward is growth hormone deficiency itself, where the pituitary gland simply doesn’t produce enough. But the list extends well beyond that. The FDA has approved it for children with Turner syndrome (a chromosomal condition affecting girls), Noonan syndrome, Prader-Willi syndrome, SHOX gene deficiency, chronic kidney insufficiency, and children who were born small for their gestational age and haven’t caught up in height. It’s also approved for idiopathic short stature, meaning children who are significantly short without a clear medical explanation.
In each of these conditions, the goal is different. For a child with true growth hormone deficiency, therapy replaces what’s missing. For conditions like Turner syndrome, the child’s body may produce normal amounts of growth hormone, but the therapy provides supra-physiological levels to push growth beyond what their body would otherwise achieve.
Growth Hormone Therapy in Adults
Adults can also develop growth hormone deficiency, either as a continuation of a childhood condition or from damage to the pituitary gland later in life (from tumors, surgery, radiation, or head trauma). In adults, the deficiency doesn’t affect height but causes a recognizable cluster of problems: increased body fat (especially around the midsection), reduced muscle mass, lower bone density, decreased exercise capacity, and diminished quality of life including fatigue and poor mood.
Treatment in adults improves body composition, exercise tolerance, bone strength, and overall well-being. The benefits tend to be most pronounced in people with more severe deficiency. Diagnosis usually requires a stimulation test unless the patient has a known genetic or structural cause that has persisted since childhood.
How the Diagnosis Is Made
Because growth hormone is released in pulses rather than at a steady rate, a single blood draw can’t reliably measure it. Instead, doctors use a stimulation test. You’re given a substance that should trigger your pituitary to release a burst of growth hormone, and then your blood is drawn at timed intervals to measure the response.
The key number is the peak level your body reaches. A normal response is at least 10 ng/mL. A peak between 5 and 10 ng/mL is considered indeterminate, and a peak below 5 ng/mL confirms a deficiency. Some labs use a slightly different cutoff of 7 ng/mL as the lower boundary of normal. For children, this test is typically done after other causes of short stature (thyroid problems, nutritional issues, chronic illness) have been ruled out.
What Treatment Looks Like Day to Day
Growth hormone is given as a subcutaneous injection, meaning a small needle goes just under the skin rather than into a muscle or vein. Most people use a pen-style device that makes the injection simple enough for parents to give to young children or for adults to self-administer. The injection is given once daily, ideally within an hour of bedtime to mimic the body’s natural pattern of releasing the most growth hormone during sleep. Consistency matters: giving the shot at roughly the same time each night, say between 9 and 10 p.m., produces the best results.
There are eight recommended injection sites: the back of both arms, the top or outer part of both thighs, both sides of the belly, and the outer quadrant of both buttocks. You rotate among four of these sites with each injection to prevent skin thickening or irritation at any one spot. For most families, the process quickly becomes routine, taking just a few minutes each night.
Monitoring During Treatment
Once treatment begins, regular blood work is essential. The primary marker doctors track is IGF-1, the downstream hormone that reflects how much growth hormone activity is happening in the body. Blood samples are drawn at least once a year, and the dose is adjusted based on the results. International guidelines recommend keeping IGF-1 levels below a specific upper threshold (2 standard deviations above the mean for age and sex) to minimize the risk of side effects. Some treatment approaches target a specific IGF-1 level rather than using a fixed weight-based dose, which can actually reduce the total amount of medication needed while still achieving good growth.
For children, doctors also track height velocity (how many centimeters gained per year), bone age via wrist X-rays, and signs of puberty. For adults, monitoring includes body composition, bone density, cholesterol levels, and blood sugar, since growth hormone influences all of these.
Common Side Effects
Most side effects of growth hormone therapy are mild. The most frequent issues are related to the injection itself: skin thickening, redness, swelling, or itching at the site. Some people experience headaches, muscle or joint pain, or symptoms that resemble a mild infection like a sore throat or cough. Hair thinning and increased gas are also reported.
More concerning side effects, though less common, include significant swelling in the hands, feet, or ankles, and numbness or tingling in the extremities. These symptoms suggest the dose may be too high and typically resolve when it’s reduced. Children on therapy should be watched for new or persistent hip or knee pain or a limp, which could signal a bone-related complication at the growth plates. Growth hormone also reduces insulin sensitivity, meaning it can nudge blood sugar levels upward. This is why glucose metabolism is monitored during treatment, particularly in patients who already have risk factors for diabetes.
How Long Treatment Lasts
For children with growth hormone deficiency, treatment typically continues until they’ve reached their final adult height or until their growth plates have closed, which usually happens in the mid-to-late teens. At that point, doctors reassess whether the deficiency persists. Some people outgrow the need for therapy; others continue into adulthood because their pituitary never produces enough on its own.
For adults diagnosed with growth hormone deficiency, treatment is generally ongoing and indefinite, since the metabolic benefits (maintaining muscle mass, bone density, and energy levels) depend on continued therapy. Adults who stop treatment often see a gradual return of symptoms over months, including increased body fat, decreased energy, and reduced bone density. The decision to continue is revisited periodically based on how well the patient responds and whether the benefits justify the commitment of daily injections.
What Results to Expect
In children, the most visible result is increased growth rate. A child who was growing 2 to 3 centimeters per year before treatment might grow 8 to 10 centimeters in the first year of therapy, with the response gradually tapering in subsequent years. The earlier treatment starts, the more total height is typically gained. Children treated for idiopathic short stature generally see more modest gains than those with true growth hormone deficiency.
In adults, the changes are less dramatic but meaningful. Body fat decreases, particularly around the abdomen. Lean muscle mass increases. Exercise capacity improves. Bone density strengthens over time, reducing fracture risk. Many adults also report better sleep, improved mood, and more energy, though these subjective benefits vary from person to person.