Growth hormone deficiency (GHD)

Growth hormone deficiency (GHD) is a disorder that occurs when the pituitary gland produces an insufficient amount of growth hormone. A rare condition that primarily affects children, GHD is seen in only about 1 in 7,000 births. Because growth hormone plays a critical role in enabling typical growth, children with GHD are likely to grow at a slower rate and appear smaller in stature than other children their age and gender. In many cases, GHD is a congenital condition that children have from birth. Non-congenital cases often occur due to brain injury, tumors, or as a result of radiation treatment. Less commonly, GHD can also occur without any clear cause. Regardless of whether it is congenital or acquired, GHD can be diagnosed and treated with relative ease. Once a diagnosis is confirmed, patients with GHD are typically required to take daily injections of synthetic human growth hormone for a variable period of time that may last into adolescence or even adulthood.

Background

GHD is tied directly to the performance of the pituitary gland. A key part of the endocrine system, the pituitary gland is a small pea-sized gland that is responsible for secreting various important hormones that regulate vital body function and support general well-being. Because of the role it plays in controlling the activity of most other endocrine glands, the pituitary gland is often referred to as the master gland. It is located in a bony hollow called the sella turcica that is found beneath the brain at the base of the skull behind the eyes. It is also attached to a small but important part of the brain known as the hypothalamus.

The pituitary gland is composed of the anterior and posterior lobes. The anterior lobe is connected to the brain via short blood vessels. The posterior lobe is part of the brain itself and commanded by the brain to directly secrete hormones into the bloodstream. Each lobe is made of different types of cells that produce and secrete various hormones. The anterior lobe produces and releases a variety of important hormones, including growth hormone, thyroid-stimulating hormone, and adrenocorticotropic hormone. Growth hormone regulates growth and physical development. Thyroid-stimulating hormone activates the thyroid to release its own hormones. Adrenocorticotropic hormone stimulates the adrenal glands to produce cortisol and other hormones. The anterior lobe also produces hormones such as prolactin, endorphins, follicle-stimulating hormone, and luteinizing hormone. Prolactin plays a key role in the production of breast milk. Endorphins are pain-relieving hormones. Follicle-stimulating hormone is tied to the production of egg cells in women and sperm cells in men. Luteinizing hormone contributes to the production of estrogen in women and testosterone in men. The posterior lobe secretes hormones that are typically produced in the hypothalamus and stored in the pituitary gland. These hormones include vasopressin and oxytocin. Vasopressin, which is also known as antidiuretic hormone, aids the body in conserving water and preventing dehydration. Oxytocin is an important female hormone that stimulates the release of breast milk and helps regulate contractions during childbirth.

Various medical conditions can affect the pituitary gland and impact its ability to properly release hormones. Issues like traumatic brain injury, tumors, or certain diseases can disrupt the pituitary gland’s functionality and lead to hormone-related conditions. One of these conditions is GHD.

Overview

GHD is a rare medical condition that results when the pituitary gland fails to produce enough growth hormone to facilitate typical growth. Growth hormone is an essential hormone that regulates growth, the development of muscle and bone strength, and the distribution of fat throughout the body. For this reason, growth hormone is particularly important in children. When growth hormone is not produced properly, a child’s growth is directly impacted.

There is no one definitive cause of GHD. In most cases, GHD can be classified as either congenital or acquired. Congenital GHD usually occurs when the pituitary gland does not form properly during early development. As such, children with congenital GHD are born with the condition. Acquired GHD arises when the pituitary gland is damaged sometime after birth. Brain tumors at or near the pituitary gland are the most common cause of acquired GHD. Traumatic brain injury, infections, or radiation treatments can also cause GHD. There is also a third form of GHD with no clear cause that is simply referred to as idiopathic.

The most obvious symptoms of GHD are related to the size of children who have it. Children with GHD are generally shorter and have younger looking faces than peers of the same age and gender. Some also have extra abdominal fat. Children who acquire GHD at a later stage of development may experience delayed puberty. As a result, adolescents with GHD often struggle with low self-esteem tied to their short stature or not maturing as quickly as their peers. Other psychological symptoms like depression, anxiety, poor memory, or lack of concentration may also occur.

Physicians typically use a battery of tests to diagnose GHD. Blood tests reveal the amount of growth hormone in the body. Hand X-rays allow doctors to assess a child’s level of bone growth. Kidney and thyroid function tests can offer insight as to how well the body is producing and using hormones. A growth hormone stimulation test can show if the pituitary gland is producing enough growth hormone. This all provides the data necessary for a doctor to determine whether or not a patient has GHD.

The treatment for GHD has evolved over time. Prior to the mid-1980s, GHD was treated with daily injections of human growth hormone extracted from the pituitary glands of cadavers. That changed with the introduction of a synthetic form of growth hormone called recombinant human growth hormone (rHGH) produced with the aid of genetically engineered bacteria. A growing number of commercially produced rHGH therapies are currently available, with some of the most common being Nutropin, Humatrope, and Genotropin. Treatment procedures often vary depending on factors like the patient’s age and medical history, the extent of his or her condition, tolerance level, and expectations. Regardless of the variables involved, treatment always requires regular injections of rHGH. Depending on the patient’s specific needs, these injections may need to be given daily, several times per week, or at some other interval. Since rHGH therapy is typically performed over the course of at least a few years, a patient’s injection schedule is likely to change over time. The treating physician will closely monitor the patient’s condition and make adjustments to the injection schedule as appropriate. In most cases, the need for treatment ceases as the patient enters adolescence and reaches the end of his or her natural growth cycle.

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