Growth hormone deficiency is a rare medical condition where the body’s pituitary gland doesn’t produce enough growth hormone, leading to slower than normal growth in children and a variety of metabolic problems in adults. While this condition can be present from birth or develop later in life, early detection and proper treatment can help many affected individuals reach normal height and improve their quality of life.
How Common Is Growth Hormone Deficiency?
Growth hormone deficiency is considered a rare condition that affects only a small portion of the population. Understanding how often it occurs helps put the condition into perspective for patients and families who may be dealing with a diagnosis.
Among children who are noticeably shorter than their peers, growth hormone deficiency occurs in approximately 1 in every 4,000 to 10,000 cases. This means that in a large school district, there might only be a handful of children affected by this condition. The rarity of the condition means that many pediatricians may only encounter a few cases throughout their careers.[1][2]
In adults, the condition is even less common. Approximately 1 in every 10,000 people develop adult-onset growth hormone deficiency. Most cases of growth hormone deficiency are initially noticed during childhood when growth patterns become a concern, though the condition can develop at any point in life.[1]
The genetic forms of growth hormone deficiency, which are passed down through families due to mutations in specific genes, are estimated to affect about 1 in 7,000 people. While most types of growth hormone deficiency occur equally in males and females, males tend to be diagnosed more often than females, though the exact reasons for this difference are not entirely clear.[3]
What Causes Growth Hormone Deficiency?
Growth hormone deficiency happens when something interferes with the normal production of growth hormone by the pituitary gland, a pea-sized organ located at the base of the brain. The pituitary gland is sometimes called the “master gland” because it produces several important hormones that control many body functions, including growth, blood pressure, energy levels, and sexual function.[6]
The causes of growth hormone deficiency can be divided into different categories based on when and how the condition develops. Understanding these causes helps doctors determine the best treatment approach and gives families insight into why the condition occurred.
Congenital causes refer to problems that are present from birth. Some babies are born with growth hormone deficiency due to genetic mutations that affect how the pituitary gland develops or how growth hormone is produced and works in the body. Genes that may be involved include GH1, GHRHR, and BTK. In some cases, congenital growth hormone deficiency occurs alongside abnormal formation of structures in the brain that happened before the baby was born. Some children with congenital deficiency may also lack other hormones produced by the pituitary gland, not just growth hormone.[2][3]
Acquired causes are those that develop during childhood or adulthood after a period of normal growth hormone production. Brain tumors in or near the pituitary gland or hypothalamus (the part of the brain that controls the pituitary) are one of the most common acquired causes. Surgery to remove these tumors or radiation therapy used to treat cancer in the brain area can damage the pituitary gland and lead to growth hormone deficiency. Severe head injuries from accidents or sports-related trauma can also damage the delicate pituitary gland.[2][4]
Certain diseases can infiltrate or inflame the pituitary gland, causing it to malfunction. For example, histiocytosis is a rare disease that can affect the pituitary area. Rarely, an autoimmune condition called hypophysitis causes chronic inflammation of the pituitary gland. This condition has been seen in some patients after treatment with certain cancer medications.[4]
In about one-third of all cases, doctors cannot identify a specific cause for the growth hormone deficiency. When this happens, the condition is called idiopathic growth hormone deficiency, where “idiopathic” is a medical term meaning “unknown cause.” Despite not knowing exactly why it occurred, these cases can still be effectively treated.[3][6]
Risk Factors for Developing Growth Hormone Deficiency
Certain factors increase the likelihood that a person will develop growth hormone deficiency. Being aware of these risk factors can help with early detection and prompt treatment.
Children who received cancer treatment before reaching their full adult height face an increased risk, especially if treatment occurred when they were very young. Radiation therapy to the head or brain is particularly concerning, especially when doses reach 18 Gy (1800 cGy/rads) or higher. Radiation fields that put children at risk include cranial (whole brain) radiation, craniospinal radiation, and radiation to areas around the nose, throat, mouth, eyes, orbits, ears, and midfacial areas. Children who received radiation before bone marrow or stem cell transplant are at especially high risk.[21]
Genetics play a role in some cases. Children whose parents or siblings have certain genetic mutations affecting pituitary gland development may be more likely to develop congenital growth hormone deficiency. Families with a history of pituitary disorders should inform their doctors so children can be monitored for signs of growth problems.[2]
Anyone who has undergone surgery on the pituitary gland or surrounding brain structures has an increased risk of developing growth hormone deficiency afterward. The delicate nature of pituitary surgery means that even when performed by skilled surgeons, there is always some risk of affecting the gland’s ability to produce hormones.[11]
People who have had traumatic brain injuries, particularly those severe enough to cause structural damage to the base of the skull where the pituitary gland sits, are at higher risk. This includes injuries from car accidents, falls, and contact sports. Even after the initial injury heals, hormone production may not fully recover.[6]
Individuals with a history of pituitary tumors, even if successfully treated, remain at risk for developing hormone deficiencies due to the tumor’s effects on surrounding normal pituitary tissue or as a result of the treatments used to manage the tumor.[11]
Signs and Symptoms of Growth Hormone Deficiency
The symptoms of growth hormone deficiency look quite different depending on whether the condition affects an infant, child, or adult. Recognizing these signs is crucial for getting proper diagnosis and treatment.
In Infants and Children
The most obvious sign of growth hormone deficiency in children is slow height growth. While growth takes place over many years and every child grows at their own pace, children with growth hormone deficiency grow much more slowly than expected. After a child’s third birthday, the main warning sign is growing less than about 1.4 inches (approximately 3.5 centimeters) in height per year. This slower growth rate becomes more noticeable as time passes and the child falls further behind their peers in height.[1][4]
Children with growth hormone deficiency typically have normal body proportions, meaning their arms, legs, and trunk are all proportionately small. This differs from some other growth conditions where certain body parts may be disproportionately affected. They often have a younger-looking face compared to other children their age, appearing more immature than their actual years would suggest.[1][4]
Physical development may be delayed in several ways beyond just height. Hair and nail growth may be slower than normal. Teeth may come in later than expected. The development of gross motor skills like standing, walking, and jumping may be delayed because muscle development is also affected by the lack of growth hormone.[1][7]
Many children with severe growth hormone deficiency have a chubbier body build with more body fat, particularly around the middle. Some may have a prominent forehead or an underdeveloped bridge of the nose. Despite these physical differences, growth hormone deficiency does not affect a child’s intelligence or mental development.[4][9]
Physical maturation may also be delayed, meaning that bone development and puberty may occur several years later than in other children. In boys born with severe growth hormone deficiency, the penis may be smaller than normal at birth, a condition called micropenis, especially when other pituitary hormones called gonadotropins are also deficient.[3]
In Adults
Growth hormone deficiency in adults causes a very different set of problems than in children, since adults have already finished growing. After the growth plates in bones have closed, growth hormone no longer affects height, but the body still needs it for many important functions related to metabolism, body composition, and overall health.[1]
Adults with growth hormone deficiency often notice changes in their body composition. They tend to have higher levels of body fat, especially around the waist and abdomen. At the same time, they lose muscle mass and strength, which affects their ability to perform physical activities. Many adults report decreased stamina and find they cannot exercise for as long or as intensely as before.[6][11]
Bone health deteriorates when growth hormone is deficient. Bone density decreases, making bones thinner and more fragile. This raises the risk of developing osteoporosis and increases the chance of bone fractures, particularly as people age.[6][9]
Changes in cholesterol and other blood fats are common. People with adult growth hormone deficiency tend to have unfavorable cholesterol patterns, with higher levels of low-density lipoproteins (the “bad” cholesterol) compared to high-density lipoproteins (the “good” cholesterol). They may also have elevated triglyceride levels, another type of fat in the blood that contributes to blocked blood vessels and increases cardiovascular risk.[11]
Many adults experience persistent physical fatigue and lower-than-normal energy levels throughout the day. They may feel exhausted even without doing strenuous activities. Some people notice they are more sensitive to both heat and cold than they used to be.[11]
Mental and emotional symptoms can be just as troubling as physical ones. Depression and anxiety are common among adults with growth hormone deficiency. Many people have trouble concentrating on tasks or lose interest in activities they need or want to do. Some feel socially isolated and lose interest in spending time with others. Memory problems may also occur.[6][11]
Sexual function may decline, with decreased interest in sexual activity. Overall quality of life often suffers significantly due to the combination of physical, mental, and emotional symptoms. It’s important to remember that not every adult with growth hormone deficiency will have all these symptoms, and some people may have few or no obvious signs, especially in mild cases.[6]
Prevention of Growth Hormone Deficiency
Because many cases of growth hormone deficiency result from genetic factors, brain tumors, or injuries that cannot be predicted or prevented, there are limited strategies for preventing the condition itself. However, there are some steps that may reduce risk in certain situations.
For children undergoing cancer treatment, doctors carefully consider the potential long-term effects of radiation therapy when developing treatment plans. When possible, they try to minimize radiation doses to the brain and pituitary area, use more targeted radiation techniques, or choose alternative treatments that don’t involve radiation to sensitive areas. However, these decisions must always balance the need to effectively treat the cancer against potential future risks.[21]
Preventing head injuries through appropriate safety measures may reduce the risk of acquired growth hormone deficiency. This includes wearing helmets during activities like cycling, skateboarding, and contact sports; using proper safety equipment in vehicles including seat belts and appropriate child car seats; and taking precautions to prevent falls, especially in young children and older adults.
For individuals with known pituitary tumors or other pituitary disorders, regular monitoring and follow-up with an endocrinologist (a doctor who specializes in hormone-related conditions) can help detect growth hormone deficiency early if it develops. Early detection allows for prompt treatment, which can prevent some of the complications associated with untreated deficiency.
While these measures may help in some cases, it’s important to understand that growth hormone deficiency often cannot be prevented, particularly when it results from genetic causes or unexpected medical events. The focus should be on early recognition and appropriate treatment rather than prevention in most cases.
How the Body Normally Produces and Uses Growth Hormone
Understanding how growth hormone normally works helps explain what goes wrong when someone has growth hormone deficiency. Growth hormone is a protein made by specialized cells called somatotrophs in the anterior (front) part of the pituitary gland. The pituitary gland is located at the base of the brain, just below the hypothalamus, and is about the size of a pea despite its crucial role in the body.[2][13]
Growth hormone production is controlled by a complex system involving the hypothalamus, which sits just above the pituitary gland. The hypothalamus releases a substance called growth hormone-releasing hormone (GHRH) that tells the pituitary to make more growth hormone. Another substance called somatostatin acts as a brake, telling the pituitary to stop or slow down growth hormone production. A third substance called ghrelin also stimulates growth hormone release, though to a lesser degree. This system operates through a complex feedback loop involving several other factors including insulin-like growth factor-1 (IGF-1), leptin, free fatty acids, and signals from the central nervous system.[2][13]
Growth hormone is released in bursts throughout the day and night rather than continuously. These bursts occur mostly during sleep, particularly during deep sleep stages. Between bursts, growth hormone levels in the blood may drop to nearly undetectable levels, which is why testing for growth hormone deficiency can be challenging.[7]
When growth hormone enters the bloodstream, it travels to the liver and other tissues. In the liver, growth hormone stimulates the production of IGF-1, which is then released into the circulation. IGF-1 works through both endocrine (traveling through the blood to distant targets) and paracrine/autocrine (acting locally where it’s made) mechanisms to promote growth. Growth hormone also stimulates local production of IGF-1 in tissues such as bone and cartilage.[2][13]
At the growth plates (epiphyses) in bones, growth hormone and IGF-1 work together to stimulate linear bone growth. They promote the differentiation of early cartilage cells called prechondrocytes and the expansion of bone-building cells called osteoblasts. This process continues throughout childhood and adolescence until the growth plates close after puberty is complete.[13]
Growth hormone affects many body functions beyond just promoting growth in children. It helps maintain normal body structure and metabolism (the chemical processes that keep the body functioning) throughout life. It plays important roles in building and maintaining muscle mass, keeping bones strong, controlling how the body distributes and uses fat, and helping to keep blood sugar (glucose) levels within a healthy range. It’s also needed for normal brain function and may play a role in regulating mood and emotions.[1][2]
When the pituitary gland doesn’t produce enough growth hormone, all these normal processes are affected. In growing children, the most obvious effect is on height, but the deficiency also impacts muscle development, body composition, and metabolic processes. In adults who have finished growing, growth hormone deficiency causes problems with body composition, metabolism, bone strength, and cardiovascular health even though it no longer affects height.[1]
Some people with growth hormone deficiency also have hypopituitarism, which means the pituitary gland doesn’t produce enough of other hormones as well. These may include antidiuretic hormone (which helps control water balance), follicle-stimulating hormone and luteinizing hormone (which affect sexual development and reproduction), thyroid-stimulating hormone (which controls the thyroid gland), and adrenocorticotropic hormone (which controls the adrenal glands). When multiple hormones are deficient, this is called combined pituitary hormone deficiency, and it requires more comprehensive treatment.[1][3]
