IGF-1 Somatomedine Growth Hormone

Somatomedine or IGF-1 Insulin-like Growth Factor I

The test determines the amount of IGF-1 in the blood. IGF-1 is a protein hormone, which is related to insulin. It is mainly made in the liver and regulates growth. The production of IGF-1 is regulated by growth hormone (GH) produced in the pituitary gland, a major hormone gland in the brain. A deficiency or excess of IGF-1 is directly related to a deficiency or excess of Growth Hormone.

The amount of IGF-1 in the blood is very much dependent on age. During childhood it rises gradually with a very high peak during puberty. IGF-1 stimulates the growth of bone length and the production of muscle tissue. Thereafter, it decreases again slightly. During the further increase of age the amount of IGF-1 decreases.

IGF-1 can be requested from:

• suspicion of a lesion or a tumour in the pituitary gland
• suspected under- or overproduction of GH
• stunted growth in children
• Treatment of GH deficiency with synthetic GH
• treatment for acromegaly

For each age there are corresponding upper and lower limits. Because there are different measurement methods that give different results, there is no single table with standard reference values.

Decreased

An IGF-1 deficiency is the result of a growth hormone (HgH) deficiency. It leads in childhood to short stature and in adults to decrease in muscle mass, osteoporosis and increase in blood cholesterol. Growth hormone deficiency is usually the result of damage to the pituitary gland or the presence of a tumor in the pituitary gland, which displaces growth hormone-producing cells.

Increased

An excess of IGF-1 results from an excess of growth hormone. It leads to excessive height growth in children who have not yet reached puberty. In adults, it leads to additional growth of hands and feet and increase in cartilage tissue. This is accompanied by a gradual enlargement of the facial features (acromegaly). Excessive production of GH is usually due to the presence of a benign GH-producing tumor in the pituitary gland.

IGF-1 is used to monitor the effect of GH suppressive therapy in acromegaly. The aim here is to obtain average IGF-1 values. The treatment of GH deficiency with synthetic GH is also followed up with IGF-1. Depending on the treatment goal, average IGF-1 values are aimed for (maintenance dose) or high-normal values (for catch-up growth in children).

see here the graph with standard deviation according to Bidlingmaier