There are various glands that an endocrine system consists of in the different parts of the body that secrete hormones straight into the blood instead into a duct system. Therefore, it is referred to as ductless glands. Hormones are not limited to one specific function, it has multiple tasks to perform in order to let the human body perform accurately. There are several effects on the different target organs by one hormone and, conversely, one target organ may be affected by more than one hormone. The medical forte of endocrinology concerns the diagnosis and evaluation of a broad multiplicity of symptoms and variations and management of the disorder and deficiencies in the long run, or excess secretion of one or more hormones by the glands.

Endocrine diseases are diagnosed and treated by running various laboratory tests to an extent which is greater than most specialities, investigation of diseases is done through excitation/stimulation or inhibition/suppression testing. This process might include injection with a stirring agent to test the position of an endocrine organ. Blood is then sampled to assess the changes in the relevant hormones or metabolites. Extensive knowledge of clinical chemistry and biochemistry is needed by endocrinologists to understand the uses and limitations of the investigations.