Growth Hormone (GH)
This test measures the amount of growth hormone (GH) in the blood. GH is a hormone produced by the pituitary gland. Growth hormone is essential for a child's normal growth and development and promotes proper linear bone growth from birth through puberty. Children with insufficient GH production grow more slowly and are smaller in size for their age. Excess GH is most often due to a GH-secreting pituitary tumor (usually benign). Too much GH can cause children's long bones to continue to grow beyond puberty, resulting in gigantism with heights of 7 or more feet tall. Those with excess GH may also have thickening of facial features, general weakness, delayed puberty, and headaches. Gigantism is an extremely rare condition. Although GH is not as active in adults, it does play a role in regulating bone density, muscle mass, and lipid metabolism. Deficiencies can lead to decreased bone densities, less muscle mass, and altered lipid levels. Excess GH in adults can lead to acromegaly, marked not by bone lengthening but by bone thickening.