Human growth hormone is required for normal bodily growth and development—growth of the bone, muscle, and cartilage cells. Also called human somatotropin (and abbreviated hGH or hST), the hormone is a protein produced by the pituitary gland. It functions by promoting RNA and protein synthesis so that cells will multiply and differentiate. Human growth hormone is also necessary for metabolism of fat, water, and minerals.

In the 1930s, the American biologist Herbert Evans (1882-1971) demonstrated how pituitary extract can greatly stimulate animal growth, producing a condition called gigantism. In the 1940s, Evans and his colleague Choh Hao Li isolated the growth hormone from cattle. Other scientists isolated growth hormones in different animal species. In 1966, Li and endocrinologist Harold Papkoff (1925-) determined the sequence of human growth hormone, showing that it has 245 amino acids. In 1970, Li and other scientists independently synthesized...