The Growth Hormone-Insulin-Like Growth Factor I Axis: Studies in Man during Growth
An individual’s linear growth and development from childhood through adolescence to adulthood is modulated by multiple hormones. In man, linear growth takes place until closure of the epiphyses but distinct periods of growth acceleration or deceleration are clearly discernable within the general pattern. Growth velocity which is greatest at birth, declines steadily until the prepubertal growth spurt, at which time a dramatic increase occurs in height velocity. As a child completes puberty, the growth rate falls once again and eventually growth ceases when the epiphyses close. Growth hormone (GH) and related growth factors, in particular, insulin-like growth factor I (IGF I) are thought to control linear growth in phases of acceleration. Since growth acceleration occurs predominantly during or shortly before puberty, the sex hormones, estrogen and testosterone, may also have an important role. Unfortunately, studies to date have usually involved pooling of subjects of multiple ages to form a broad age range and in no single study has a sufficient number of subjects been studied to yield truly interpretable data. Our current study was conducted in over 3,000 children and adolescents spanning the ages from birth through 16 years. This study was motivated from preliminary data, suggesting there may be two clearly different patterns of interaction between hormones and receptors, one pattern regulating growth in boys, another in girls.
KeywordsGrowth Hormone Growth Hormone Level Height Velocity Growth Hormone Concentration Growth Acceleration
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