Growth hormone deficiency (GHD) is a condition where the pituitary gland, a pea-sized structure at the base of the brain, produces too little growth hormone. In children, this leads to noticeably slow growth and short stature. In adults, it affects body composition, energy levels, bone strength, and cardiovascular health. The condition can be present from birth or develop later in life due to injury, tumors, or other damage to the pituitary gland.
How Growth Hormone Works
Growth hormone does far more than drive childhood height. It regulates how your body builds muscle, breaks down fat, maintains bone density, and manages cholesterol. The pituitary gland releases it in pulses throughout the day, with the largest bursts happening during deep sleep. Once released, growth hormone signals the liver to produce a secondary hormone called IGF-1, which carries out many of its effects in tissues throughout the body.
When the pituitary gland can’t produce enough growth hormone, or when the brain fails to properly signal the gland to release it, the downstream effects ripple across multiple body systems. The severity depends on how much hormone is actually being produced. Some people make very little, while others have a partial deficiency that causes subtler problems.
Causes in Children and Adults
GHD falls into two broad categories: congenital (present at birth) and acquired (developing later). Some children are born with genetic mutations that directly impair growth hormone production. The GH1 gene, for example, provides instructions for making the growth hormone protein itself. Mutations in this gene cause more than one type of isolated GHD. Other mutations affect the receptor that allows the brain’s releasing signal to reach the pituitary gland, essentially cutting off communication. In rare cases, children are born without a fully formed pituitary gland.
Acquired GHD is more common and has a wider range of triggers. Pituitary tumors (or surgery and radiation to treat them) are the leading cause in adults. Traumatic brain injury, infections affecting the brain, and reduced blood flow to the pituitary can also damage the gland enough to reduce hormone output. Sometimes no specific cause is found, which doctors call idiopathic GHD.
Signs in Children
The most visible sign is falling behind in height compared to peers. Pediatric guidelines define concerning short stature as a height more than 2 standard deviations below the average for age and sex, or a growth rate that has noticeably slowed over time. For context, children over age 2 should generally grow at least 4 centimeters (about 1.5 inches) per year, though the exact expected rate varies by age and sex. A child who was tracking along a normal growth curve and then plateaus, or who is significantly shorter than expected based on their parents’ heights, warrants evaluation.
Height isn’t the only clue. Children with GHD often look younger than their actual age. They may have a rounder face, more body fat around the midsection, and delayed tooth development. Bone maturation lags behind, meaning their skeleton appears younger than it should on an X-ray. In boys, puberty may be delayed. These children are typically proportional (their limbs and torso grow at similar rates), which helps distinguish GHD from other causes of short stature where proportions are uneven.
Signs in Adults
Adult-onset GHD is easier to miss because the symptoms overlap with many other conditions. The hallmark changes involve body composition: increased fat mass (particularly around the abdomen), decreased lean muscle, and reduced muscle strength. Many adults also experience low energy, poor exercise tolerance, and a general sense of reduced well-being that’s sometimes mistaken for depression or normal aging.
The effects extend beyond what you can see in the mirror. Bone mineral density drops, raising the long-term risk of osteoporosis and fractures. Cholesterol profiles shift unfavorably, with higher LDL and total cholesterol. Some research links GHD to enhanced cardiovascular risk overall. Adults with untreated deficiency also report poorer sleep quality and difficulty with concentration and memory, though these are harder to measure objectively.
How GHD Is Diagnosed
Diagnosis isn’t as simple as a single blood draw, because growth hormone is released in pulses and fluctuates dramatically throughout the day. A random blood sample could show low levels even in a healthy person. Instead, doctors rely on a combination of clinical evaluation, blood markers, and specialized stimulation tests.
IGF-1 Screening
The first step is usually measuring IGF-1, the hormone produced by the liver in response to growth hormone. Because IGF-1 levels are more stable throughout the day, they serve as a useful screening tool. However, “normal” IGF-1 ranges vary significantly by age, sex, and pubertal stage. Levels naturally peak during adolescence and decline steadily through adulthood. A low IGF-1 level raises suspicion but doesn’t confirm the diagnosis on its own. It’s also important that follow-up tests use the same laboratory method, since different assays can produce meaningfully different numbers for the same patient.
Stimulation Tests
To confirm GHD, doctors use stimulation tests that provoke the pituitary gland into releasing growth hormone, then measure the response. The insulin tolerance test is considered the gold standard for both children and adults. It involves giving insulin to lower blood sugar, which normally triggers a strong growth hormone release. In adults, a peak growth hormone level below 3 to 5 micrograms per liter during adequate low blood sugar confirms deficiency.
Body weight affects interpretation. In overweight and obese adults, the threshold is lower (1 microgram per liter or below) because excess body fat independently suppresses growth hormone responses. Using the standard cutoff in heavier patients would lead to overdiagnosis. Alternative tests, like the glucagon stimulation test, are available for people who can’t safely undergo insulin-induced low blood sugar, such as those with epilepsy or heart disease.
Treatment With Growth Hormone Replacement
The standard treatment is daily injections of synthetic growth hormone, a lab-made version identical to what the pituitary gland naturally produces. In children, the goal is to restore normal growth velocity and help them reach an adult height within their genetic potential. In adults, treatment targets improvements in body composition, bone density, cholesterol, energy, and quality of life.
Children typically receive weight-based doses, while adults start at a lower fixed dose that’s gradually increased based on how they respond. The final maintenance dose varies from person to person and is guided by symptom improvement, side effects, and IGF-1 levels measured through periodic blood tests. Treatment in children continues until they’ve finished growing or until re-testing shows the deficiency has resolved (which happens in some cases of childhood-onset GHD). Adults with confirmed persistent deficiency may need treatment indefinitely.
What to Expect During Treatment
Growth hormone is given as a subcutaneous injection, typically at bedtime to mimic the body’s natural release pattern during sleep. Most children and adults learn to self-administer using pen-style injection devices. The needles are small, and discomfort is generally mild.
In children, the response is usually visible within the first 6 to 12 months as growth rate accelerates. Doctors monitor for specific side effects at each follow-up visit, including increased pressure in the skull (which can cause headaches and vision changes), a condition where the top of the thigh bone slips at the growth plate, and worsening of any existing spinal curvature. These are uncommon but require prompt attention if they occur.
Adults may notice fluid retention, joint stiffness, or tingling in the hands during the first weeks of therapy, especially if the dose is increased too quickly. These effects usually resolve with dose adjustment. Because growth hormone interacts with other hormonal systems, doctors also re-check thyroid and adrenal function after starting treatment, particularly in patients whose pituitary problems could affect multiple hormones. IGF-1 levels are measured periodically to ensure the dose is producing appropriate levels without pushing them too high.
Long-Term Risks of Untreated GHD
Left untreated in children, GHD results in significantly reduced adult height, potentially well below the range predicted by family genetics. The impact goes beyond stature. Bone density may never reach its full peak, setting the stage for earlier osteoporosis. Unfavorable cholesterol levels and increased abdominal fat raise cardiovascular risk that accumulates over decades. In adults, untreated GHD is associated with reduced quality of life scores, persistent fatigue, and body composition changes that are difficult to reverse through diet and exercise alone. Growth hormone replacement doesn’t eliminate all of these risks, but it meaningfully improves most measurable outcomes when started early and maintained consistently.