Endocrine disorders involve either too much or too little hormone secretion. Disorders may result from a problem in the gland itself, or because the hypothalamic-pituitary axis provides too much or too little stimulation. Depending on the type of cell they originate in, tumors can produce excess hormones or squeeze out normal glandular tissue, decreasing hormone production. Sometimes the body's immune system (see Autoimmune Disorders) attacks an endocrine gland, decreasing hormone production.

Doctors usually measure levels of hormones in the blood to tell how an endocrine gland is functioning. Sometimes blood levels alone do not give enough information about endocrine gland function, so doctors measure hormone levels after giving a stimulus (such as a sugar-containing drink, a drug, or a hormone that can trigger hormone release) or after having the patient take an action (such as fasting).

Last full review/revision May 2006 by John E. Morley, MB, BCh