The endocrine system consists of several glands, all and in different parts of the body, that secrete hormones directly into the blood rather than into a duct system. Hormones have many different functions and modes of action; one hormone may have several effects on different target organs, and, conversely, one target organ may be affected by more than one hormone. The diagnosis and treatment of endocrine diseases are guided by laboratory tests to a greater extent than for most specialties. Some of the most common endocrine diseases include diabetes mellitus, hypothyroidism and the metabolic syndrome. Life biological assays are very effective to diagnose the endocrine imbalances in the body with high sensitivity and specificity.