Growth hormone deficiency (GHD) is a condition in which the pituitary gland fails to produce enough growth hormone, a protein that drives physical growth in children and continues to regulate body composition, metabolism, and heart function throughout adulthood. It can appear at birth, develop during childhood, or emerge later in life after damage to the pituitary gland. In children, the hallmark sign is unusually slow height growth. In adults, the effects are subtler but no less significant, including increased body fat, reduced muscle mass, and a higher risk of cardiovascular problems.
How Growth Hormone Production Works
Growth hormone is made by the pituitary gland, a pea-sized structure at the base of the brain. The process starts when the brain releases a signaling molecule called growth hormone releasing hormone, which binds to specialized receptors on pituitary cells and triggers them to produce and release growth hormone into the bloodstream. From there, growth hormone stimulates the liver and other tissues to produce a secondary messenger called IGF-1, which carries out much of the actual work of promoting bone growth, building muscle, and regulating how the body processes fat and sugar.
A breakdown at any point in this chain can cause deficiency. Some people are born with gene mutations that directly impair the production of the growth hormone protein itself. Others have mutations affecting the receptor that responds to the brain’s release signal, meaning the pituitary never gets the message to start producing. In roughly half of people with one inherited form of the condition, the pituitary gland itself is physically underdeveloped.
What Causes It
GHD falls into two broad categories: congenital (present from birth) and acquired (developing later in life).
Congenital GHD is typically caused by genetic mutations. The two most commonly involved genes are the one responsible for making the growth hormone protein and the one that builds the receptor for the brain’s release signal. When either gene is faulty, the pituitary either can’t make growth hormone or can’t respond to the instruction to release it. Some cases are inherited from parents, while others arise from new mutations.
Acquired GHD in adults is most often caused by pituitary tumors. Data from a large international database of patients receiving growth hormone therapy found that pituitary tumors and a related tumor called craniopharyngioma accounted for about 65% of adult cases. It’s not always the tumor itself that causes the damage. Surgery to remove the tumor or radiation therapy aimed at the pituitary region can destroy the hormone-producing cells. Other recognized causes include traumatic brain injury (which may cause GHD in 6 to 20% of cases), bleeding around the brain, inflammatory conditions, and, in a growing number of patients, no identifiable cause at all. Idiopathic cases, where no clear trigger is found, have been increasing in recent years.
Signs in Children
The most obvious sign of GHD in children is slow growth after age three. A child with this condition typically grows less than about 1.4 inches per year, noticeably behind the pace of their peers. Over time, this gap widens and becomes more apparent. Other physical signs include a younger-looking face than expected for their age, delayed tooth development, slow hair and nail growth, and delayed puberty. These children are usually proportional in build, meaning their limbs and torso are in normal proportion to each other, just smaller overall.
Doctors often use a hand X-ray to assess bone age, which reveals how far along the skeleton is in its development compared to chronological age. In children with GHD, bone age is typically delayed, meaning the bones look younger than they should. This actually represents a window of opportunity: because the growth plates haven’t closed yet, treatment can still help a child gain meaningful height.
Signs in Adults
Adults with GHD don’t shrink, but the condition reshapes their body and erodes their quality of life in ways that are easy to blame on aging or stress. The most consistent change is in body composition: adults with GHD carry about 7% more total body fat than people with normal growth hormone levels, and that extra fat tends to concentrate around the abdomen, increasing the waist-to-hip ratio. At the same time, muscle mass and strength decline.
Exercise capacity drops significantly. Studies have shown a 20 to 25% reduction in exercise capacity compared to healthy adults, partly because growth hormone deficiency weakens the heart muscle and reduces its pumping efficiency. Cholesterol levels shift in an unfavorable direction, with higher levels of LDL (“bad” cholesterol) and triglycerides and lower levels of HDL (“good” cholesterol). Over time, these changes thicken artery walls and increase the risk of heart attack and stroke.
Beyond the physical changes, many adults with GHD report persistent fatigue, poor sleep, low motivation, difficulty concentrating, and a general decline in well-being. Bone density also decreases, raising the risk of fractures. Because these symptoms overlap with so many other conditions, adult GHD often goes undiagnosed for years.
How It’s Diagnosed
Growth hormone levels fluctuate throughout the day, spiking during sleep and exercise and dipping to near zero at other times. A single blood draw can’t reliably measure whether someone is producing enough. Instead, doctors use stimulation tests that provoke the pituitary into releasing as much growth hormone as it can, then measure the peak output.
The gold standard is the insulin tolerance test. During this test, insulin is injected to lower blood sugar, which is a powerful stimulus for growth hormone release. If blood sugar drops below 40 mg/dL and the pituitary still can’t produce a growth hormone peak above 3 to 5 micrograms per liter, deficiency is confirmed. The exact cutoff depends on the guideline used and the patient’s body weight, since obesity blunts the growth hormone response. For people with a BMI over 30, some guidelines use a stricter threshold of 1 microgram per liter to avoid false positives.
Doctors also check IGF-1 levels as a screening tool, since IGF-1 reflects overall growth hormone activity and stays more stable throughout the day. Normal IGF-1 ranges decline with age. For a person in their twenties, a typical range runs from roughly 128 to 416 ng/mL, while someone in their sixties might fall between 59 and 199 ng/mL. A low IGF-1 level raises suspicion, but a normal result doesn’t completely rule out GHD, so stimulation testing is still needed to confirm the diagnosis.
Treatment With Growth Hormone Replacement
The primary treatment is daily injections of synthetic growth hormone, a lab-made version of the protein the body should be producing on its own. Treatment typically starts at a low dose and is increased gradually over several months, with adjustments based on blood tests and how the patient responds. The goal is to restore growth hormone to levels that reverse the symptoms of deficiency without overcorrecting.
In children, the main objective is catching up on height growth before the growth plates close. Treatment is most effective when started early and continued through puberty. In adults, the goals shift to improving body composition, strengthening bones, boosting exercise capacity, and restoring quality of life. Many patients see meaningful improvements in bone density, energy levels, and the ability to exercise. Abdominal fat tends to decrease while muscle mass increases.
Side Effects of Treatment
The most common side effects of growth hormone injections relate to fluid retention: swelling in the hands, feet, or ankles, along with joint or muscle pain and numbness or tingling in the hands. These effects are typically dose-related and often improve when the dose is lowered. Some people experience headaches, skin thickening at the injection site, or mild redness and irritation where the needle goes in.
Regular monitoring is part of the treatment process. Your doctor will check IGF-1 levels periodically to make sure the dose keeps you in the target range, along with blood sugar and lipid panels to track metabolic changes. Because growth hormone influences how the body processes sugar, glucose levels need watching, particularly in people who are already at risk for diabetes.