Growth Hormone

Growth hormone is a chemical messenger made by the pituitary gland, a small gland at the base of the brain. It helps children grow taller and helps people of all ages maintain healthy muscles, bones, and metabolism. Because this hormone is released in bursts throughout the day—especially during sleep—a single blood test result can be misleading, and doctors usually need special tests to accurately assess whether levels are too high or too low. Too much growth hormone over time can cause a condition called acromegaly, which leads to changes in facial features, enlarged hands and feet, and health problems like diabetes and heart disease. Too little growth hormone can slow growth in children and cause changes in body composition and energy levels in adults.

When elevated: Persistently elevated GH levels suggest autonomous GH hypersecretion, most commonly from a GH-secreting pituitary adenoma, leading to acromegaly in adults or gigantism in children. Elevated GH may also be seen physiologically during exercise, hypoglycemia, fasting, or stress, and pathologically in conditions such as ectopic GHRH secretion or rarely ectopic GH production. Acromegaly is associated with increased risk of cardiovascular disease, diabetes mellitus, sleep apnea, arthropathy, and certain malignancies. When low: Low or undetectable GH levels, particularly in the context of failed stimulation testing, indicate GH deficiency, which may be isolated or part of combined pituitary hormone deficiency (hypopituitarism). In children, GH deficiency is a recognized cause of growth failure and short stature. In adults, GH deficiency is associated with increased visceral adiposity, reduced lean body mass, decreased bone mineral density, dyslipidemia, and impaired quality of life.

Growth hormone supports muscle protein synthesis, fat loss, and recovery from training stress, making it relevant to athletic performance and body composition. GH also influences sleep quality and metabolic adaptation to training load, though single measurements have limited practical value since secretion is pulsatile and varies with circadian rhythm, nutrition, and exercise timing.