Endocrinology is a branch of medicine dealing with disorders of the endocrine system and its specific secretions called hormones. Although every organ system secretes and responds to hormones (including the brain, lungs, heart, intestine, skin, and the kidney), the clinical speciality of endocrinology focuses primarily on the endocrine organs, meaning the organs whose primary function is hormone secretion. These organs include the pituitary, thyroid, adrenals, ovaries, testes, and pancreas. An endocrinologist is a doctor who specialises in treating disorders of the endocrine system, such as diabetes, hyperthyroidism and many others.

The medical speciality of endocrinology involves the diagnostic evaluation of a wide variety.