Growth Hormone Deficiency (GHD) is a medical condition where the pituitary gland fails to produce sufficient amounts of growth hormone (GH) necessary for normal growth and development during childhood. This hormone stimulates linear growth, increases bone density, and influences body composition. While it is a rare condition, affecting approximately one in 4,000 to 10,000 children, GHD is highly treatable. Early identification and intervention with replacement therapy can significantly improve a child’s eventual adult height and overall health.
Identifying the Signs
The most obvious indication of Growth Hormone Deficiency is a noticeably slow rate of growth, often referred to as growth failure. A pediatrician typically tracks a child’s height and weight on specialized growth charts, and a consistent pattern of falling off the expected growth curve is a primary concern. For instance, a child may be growing less than 2 inches (5 cm) per year between the ages of four and eight, which is significantly below the average pace.
Children with GHD often display physical characteristics that make them look younger than their actual age when compared to their peers. They tend to maintain normal body proportions, but they may have a relatively chubby body build, particularly around the waist. This is due to the lack of growth hormone, which also helps regulate body fat distribution. Other signs can include delayed tooth development and a noticeable delay in the onset of puberty.
Underlying Causes and Mechanisms
Growth hormone production is orchestrated by two key structures in the brain: the hypothalamus and the pituitary gland. The hypothalamus releases Growth Hormone-Releasing Hormone (GHRH), which signals the pituitary gland to synthesize and secrete Growth Hormone (GH). A disruption at any point in this signaling pathway can lead to a deficiency.
The causes of GHD are broadly classified as either congenital or acquired. Congenital GHD is present from birth and may be the result of genetic mutations or structural issues in the brain that affect the development of the pituitary gland or hypothalamus. Acquired GHD develops later in life due to damage to the pituitary gland or surrounding brain tissue.
Acquired causes can include central nervous system infections, severe head trauma, or therapeutic radiation directed at the head. Tumors near the pituitary can also physically impair the gland’s ability to produce or release GH. In many cases, however, no clear cause is ever identified, and the condition is classified as idiopathic GHD.
Diagnostic Procedures
Diagnosing Growth Hormone Deficiency involves a multi-step process that a pediatric endocrinologist oversees, beginning with a detailed review of the child’s growth history. Initial laboratory work involves measuring the levels of Insulin-like Growth Factor-1 (IGF-1) and Insulin-like Growth Factor Binding Protein-3 (IGFBP-3) in the blood. These proteins are produced by the liver and other tissues when stimulated by GH, and their levels are generally more stable than GH itself, which is secreted in short, unpredictable bursts.
Another standard diagnostic tool is the bone age X-ray, usually of the left hand and wrist. This test compares the skeletal maturity of the child’s bones to their chronological age; in children with GHD, the bone age is significantly delayed. While the initial blood tests and X-rays are highly suggestive, the definitive diagnostic tool is the Growth Hormone stimulation test.
During a stimulation test, the child is given a medication that triggers the release of GH from the pituitary gland. Blood samples are collected at specific intervals over a few hours to see if the peak GH level reaches a predetermined threshold. If the GH level does not rise adequately after the stimulus, it confirms a deficiency. Finally, an MRI of the brain and pituitary gland may be ordered to check for any structural abnormalities, tumors, or malformations that could be the underlying cause.
Growth Hormone Therapy
The standard treatment for Growth Hormone Deficiency is the replacement of the missing hormone using a synthetic version called recombinant human growth hormone. This synthetic hormone is structurally identical to the GH naturally produced by the body. The primary goal of this therapy is to normalize the child’s growth velocity, allowing them to achieve a height within the expected range for their family.
Somatropin is administered via a small, subcutaneous injection, typically once per day. The injections are usually given in the evening, as this mimics the natural peak of GH secretion that occurs during deep sleep. The weekly dose is individualized based on the child’s body weight and the specific diagnosis.
Parents or caregivers are taught how to perform the injections at home, and adherence to the daily schedule is important for the therapy’s success. In the first year of treatment, many children experience a period of rapid “catch-up” growth, with height velocity sometimes increasing to 8 to 10 cm per year. Treatment generally continues until the child reaches their final adult height, confirmed when their growth plates have closed or fused. Beyond increasing height, the therapy also helps to improve body composition by increasing lean muscle mass and decreasing fat mass.
Monitoring and Long-Term Management
Once Growth Hormone Therapy begins, monitoring is necessary to ensure the treatment is effective. Follow-up appointments with a pediatric endocrinologist are generally scheduled every three to six months. At these visits, the child’s height is measured to track the growth rate, which is the most important parameter for assessing the treatment’s success.
Blood tests are also performed periodically to measure IGF-1 levels, which helps the doctor determine if the somatropin dosage needs adjustment. The goal is to keep the IGF-1 levels within a safe and effective range. While rare, potential side effects are monitored, including headaches, signs of increased pressure in the head, or hip issues such as slipped capital femoral epiphysis.
When the child completes their linear growth, the need for continued GH treatment must be reassessed because the hormone has metabolic benefits that extend into adulthood. If the deficiency is confirmed to persist, the patient will transition to an adult endocrinologist for long-term management. Continued GH therapy in adulthood helps maintain body composition, bone mineral density, and metabolic health.