Insulin-like growth factor

Insulin-like Growth Factor I (IGF-I) is a hormone produced by the liver and pancreas. In many ways, IGF-I functions like insulin, a hormone produced by the pancreas that helps the body regulate blood glucose, also known as blood sugar. IGF-I stimulates sugar uptake in the blood and other organs.

IGF-I is prescribed to treat IGF-I deficiency, which causes stunted growth, as well as type-1 diabetes, which can be fatal. IGF-I has also been used with growth hormones as a performance-enhancing drug by athletes. Misuse of IGF-I may lead to hypoglycemia, which is low blood sugar.

Background

The history of IGF-I is closely linked to the history of insulin and diabetes. The symptoms of diabetes were first noted in the seventeenth century, but scientists did not begin to understand the disease until 1869. German medical student Paul Langerhans discovered that the pancreas in many diabetes victims had damaged beta cells. Other scientists then experimented by removing the pancreas in animals. Once the organ was removed, the animals immediately began showing symptoms of diabetes. Thus, they concluded that diabetes was caused by a malfunctioning pancreas.

Soon afterwards, scientists realized that the pancreas actively secreted a hormone. This hormone, later called insulin, plays an important role in the regulation of blood sugar. If the body is not absorbing enough blood sugar, it will not have enough fuel to carry out its basic functions. However, too much blood sugar can result in organ damage and death. Medical researchers then realized that by injecting diabetes patients with insulin, they could mitigate the symptoms of diabetes.

Later, medical researchers discovered that insulin was not the only a chemical regulating blood sugar. It worked in conjunction with IGF-I, as well as with several other hormones. IGF-I quickly became useful in treating type-1 diabetes and hormone disorders in children as well as regulating blood sugar levels. It also was used by athletes as a performance-enhancing drug.

Insulin-Like Growth Factor

Through studying insulin, researchers found a family of hormones that chemically functioned in a similar manner. IGF-I is produced in the liver and its surrounding tissues, not the pancreas. However, IGF-I binds to the same receptors as insulin, allowing it to function similarly. It also interacts with insulin and other endocrine-system hormones, allowing it to influence how the body functions in a variety of ways.

IGF-I is a peptide hormone that couples with growth hormones to control the human body's level of insulin, and thus the body's level of blood sugar. Growth hormones have been tied to reduced insulin sensitivity, while IGF-I has been shown to counteract that reaction. IGF-I increases general sensitivity to hormones, such as insulin and growth hormones.

In addition to its natural effects within the human body, IGF-I's interactions with growth hormones make it exceptionally useful to athletes, who may use it in conjunction with growth hormones or anabolic steroids to increase muscle growth and endurance and decrease recovery times. Additionally, supplementing with IGF-I alone is commonly reputed to reduce muscle recovery time, increase muscle growth, and stimulate bone growth. However, IGF-I may also lower the body's general metabolic rate, increasing the potential for weight gain. While these substances are banned by most professional sporting organizations, they are sometimes utilized by amateur-level athletes.

Because of IGF-I's interactions with insulin, an excess of the hormone has the potential to cause hypoglycemia, a condition in which blood sugar drops to lower than normal levels. The condition has a large number of potential symptoms. Victims of mild hypoglycemia experience sweating, unusual levels of hunger, irritability, confusion, disorientation, aggression, muscle weakness, difficulty concentrating, and an irregular heartbeat. Victims of severe hypoglycemia may suffer seizures and unconsciousness. If hypoglycemia is suspected, patients should immediately contact their doctor. They should also eat foods containing carbohydrates, which are quickly broken down by the body. A rush of carbohydrates will quickly raise blood sugar levels, mitigating the symptoms of hypoglycemia.

IGF-I deficiency is a disorder commonly diagnosed in children. The primary method of diagnosis of an IGF-I deficiency is a child's size. If children are smaller than 97.5 percent of their peers, they should be investigated for a hormone deficiency. If children lack the proper amounts of IGF-I during puberty, the body's naturally released growth hormone will not have the proper effect. Their bones and muscles grow less, resulting in an abnormally small child. The FDA has approved several medications to treat IGF-I deficiency. Most are given intravenously through an injection. These medications have been proven to boost growth rates to nearly normal levels in many IGF-I deficient children.

IGF-I is sometimes used in diabetes treatment. The two most common variants of diabetes are type-1 diabetes and type-2 diabetes. In type-1 diabetes, the body grows gradually more resistant to the effects of insulin. Because insulin allows the body to absorb blood sugar, blood sugar levels quickly rise, which damages bodily organs. Eventually, the organs cease to function, causing death. Type-1 diabetes can be treated with insulin injections. However, as the body's resistance to insulin grows, patients need to inject more and more insulin to obtain the same effect. Injections of IGF-I can lower insulin resistance, reducing the amount of insulin necessary for treatment. Type-2 diabetes is caused by damage to the insulin-producing sections of the pancreas and cannot be treated with IGF-I.

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