[Factors affecting human growth]

Growth is a complex phenomenon that is affected not only by growth hormone but also by thyroid hormone, androgens, glycocorticoids and insulin. It is also affected by extrinsic and genetic factors. In humans there are two periods of rapid growth, the first in infancy and the second in late puberty just before growth stops. The first period of accelerated growth is partly a continuation of the fetal growth period which is not influenced by the presence of growth hormone. The second is a period in which hormones from the gonads and the adrenal glands combine with growth hormone to produce the adolescent growth spurt. As growth is one of the major factors influencing the plan and results of orthodontic treatment, the authors of this paper attempt a vast review of the factors influencing human growth classifying them into 3 main categories i.e. endocrine glands, heredity and environment, but also evaluating, as well, the combined implications of both genetic and environmental factors.