An excess of growth hormone (GH) results in accelerated growth and in childhood, the clinical manifestation is gigantism. When GH excess has its onset after epiphyseal fusion at puberty, the overgrowth of soft tissue and bone results in acromegaly. This volume covers various topics related to growth hormone and its associated disorder when there is a GH excess, including their pathophysiology, clinical presentation and diagnosis. The volume includes a total of 8 chapters that provide a comprehensive overview of the synthesis, regulation, and various disorders related to growth hormone, including acromegaly and gigantism. The chapters have been written by experts in the field of pituitary tumors. - Growth hormone releasing hormone (GHRH) stimulates GH synthesis and secretion while somatostatin (SST) inhibits GH production and release. GH stimulates IGF-I production that inhibits GH secretion at hypothalamic and pituitary levels. - Acromegaly is a rare, adult-onset endocrine disorder caused by GH hypersecretion by the pituitary gland and it is usually due to a pituitary tumor. - Gigantism is a rare condition that occurs in children and it is caused by the overproduction of GH before the growth plates of the long bones have closed, leading to excessively tall stature and rapid growth.