The endocrine system is comprised of specialized glands, organs and body tissues that synthesize, store and secrete hormones – chemical substances that act as messengers to transmit information and commands from one cell, or a group of cells, to another.
The main human endocrinal glands are comprised of the hypothalamus, pituitary, parathyroid, adrenal and pineal body. The testes and the ovaries comprise the reproductive glands of the system. The hypothalamus, located deep inside the brain, is considered to be the chief link between the nervous and endocrine system and coordinates of the release of hormones. The pancreas, an exocrine gland located behind the stomach which secretes pancreatic juice and insulin, is often considered as part of the endocrine system.
The hormones produced by the endocrine system have a profound influence over organ functioning and the body as a whole. The numerous responsibilities of endocrinal hormones include:
- Regulating growth and development of the body
- Controlling tissue function
- Supporting pregnancy and other functions related to reproduction
- Regulating metabolism, the way the body burns energy to sustain life
Endocrine glands do not have ducts to connect them to specific organs. They release hormones directly into the blood in contrast to exocrine glands like sweat and salivary glands, which release their secretions directly into the concerned organ. As such, diagnostic tests of the endocrine system form an integral part of laboratory testing where the cause of illness is not easily determinable.
For example, extraordinary weight loss or gain is a common medical condition that evades explanation at times. Dedicated blood tests to check levels of thyroid hormones help in establishing the state of your thyroid health. It helps to understand whether the disturbances in weight are due to a thyroid condition.
The main function of the thyroid is to produce and secrete thyroxine and triiodothyronine, the two hormones that greatly affect the way the body grows and metabolizes nutrients. A simple test to check the level of these two in the blood lets the doctor know the prevalence of thyroid problems like hyperthyroidism and hypothyroidism. Further confirmation is done by checking whether the level of thyroid stimulating hormone that is secreted by the anterior pituitary to control the production of thyroid hormones.
Diagnostic tests for checking hormone levels are recommended for determining hidden causes of diseases that defy explanation such as adrenal dysfunction that manifests only as below optimal general health in adults. Similarly, lack of primary hormones like estrogen, progesterone and testosterone secreted by ovaries and testis leads to vague symptoms of mood swings, loss of sex drive and menstrual irregularities. There are specific tests like saliva hormone profiles and blood DHEA for checking the level of nearly all hormones in the body.