In order to understand why adults do not have gigantism, it is important to first understand the role of growth hormone in the body and how it affects bone growth.
Growth hormone, also known as somatotropin, is produced by the pituitary gland, a small gland located at the base of the brain. It plays a crucial role in stimulating the growth and development of bones, muscles, and other tissues throughout childhood and adolescence.
During childhood, when excess growth hormone is produced, it leads to a condition called gigantism. In individuals with gigantism, the excess hormone causes the long bones of the body, such as those in the arms and legs, to continue growing beyond their normal size. This results in an abnormal increase in height.
However, once the growth plates in the long bones close, usually around the end of puberty, the bones can no longer grow in length. As a result, the increase in bone size is limited to certain areas of the body, namely the hands, feet, and face. This condition is known as acromegaly.
Unlike gigantism, where the entire body grows excessively, acromegaly primarily affects the bones in the extremities and the facial bones. This is because the growth plates in these areas do not close during puberty, allowing the bones to continue growing in size.
The reason why adults do not experience gigantism, even with excess growth hormone, is because the growth plates in their long bones have already closed. Once the growth plates close, the bones can no longer increase in length, and any excess growth hormone will primarily affect the bones in the hands, feet, and face.
It is worth noting that acromegaly can still lead to significant changes in appearance and physical health in adults. The increased bone size in the hands and feet can cause enlargement and deformities, while the facial bones may become more prominent. Additionally, soft tissues such as the organs and skin can also be affected, leading to various health issues.
Adults do not have gigantism because their growth plates have already closed, preventing the long bones from increasing in length. Instead, any excess growth hormone primarily affects the bones of the hands, feet, and face, leading to a condition called acromegaly.