Endocrinology Explained
Glenn Carter
Dr Glenn Carter, HPG (Healthcare Professionals Group), Managing Director/Owner
Endocrinology is the study of hormone-producing tissues and hormone-related diseases. The major endocrine glands include the adrenals, pituitary, ovaries, testes, pancreas and thyroid. The hormones produced, and released into the blood, regulate a number of bodily functions including metabolism, growth, reproduction and blood pressure.
Endocrinology is the study of hormone-producing tissues and hormone-related diseases.
Many different roles, across the healthcare sector, require an appreciation of the specialty of endocrinology. Pharmaceutical and medical technology companies are involved in the research and development of innovative new treatments for a range of endocrine disorders; scientific companies provide diagnostic and laboratory equipment; the primary care and acute setting generally first diagnoses patients and provides emergency support; allied health professionals are involved in the on-going management of symptoms and the provision of dietary and lifestyle advice; and clinical endocrinologists provide specialist diagnosis and management. In assessing patients an endocrinologist will use a range of diagnostic laboratory tests to assess hormone levels and their medical management focuses on providing long term care because of the chronic and evolving nature of the diseases.
Many different roles, across the healthcare sector, require an appreciation of the specialty of endocrinology
Endocrine disorders fall into 3 main groups: 1. hyposecretion (where the endocrine gland doesn’t produce enough hormone); 2. hypersecretion (where the gland produces too much hormone) and 3. tumors of the gland (either benign or malignant).
In this article I'd like to provide a brief explanation of the various endocrine glands.
Adrenal Glands
The adrenal glands are located on the top of the kidneys, and secrete corticosteroids (involved in stress responses, inflammation and the immune system); catecholamines (eg noradrenaline and adrenaline, in response to stress); aldosterone (which affects kidney function); and androgens (eg testosterone). Hyposecretion of the adrenal gland leads to weight loss, loss of energy, mineralocorticoid deficiency and Addison’s disease. Hypersecretion of the adrenal gland leads to raised blood pressure, sweating and Cushing’s disease.
Hypothalamus
The hypothalamus is located in the brain and is involved in controlling respiration, heart rate, appetite, sleep, and temperature. The hypothalamus produces anti-diuretic hormone (ADH) – responsible for controlling water reabsorption from the kidneys, and blood pressure; and oxytocin – responsible for stimulating uterine contractions and milk secretion. Both ADH and oxytocin are produced in the hypothalamus and stored in the posterior pituitary gland.
Ovaries
The ovaries, located on either side of the uterus secrete estrogen and progesterone which promote and control sexual development, fertility and menstruation.
Testes
The testes, located in the scrotum, secrete androgens, mainly testosterone. Androgens control sexual development, puberty, sexual behaviour and the formation of sperm cells.
Pancreas
The pancreas is located in the abdomen and releases insulin (for carbohydrate and fat metabolism); somatostatin (which controls the secretion of insulin, gastrin and growth hormone; and regulates endocrine and nervous system function); and glucagon (which raises blood glucose levels when they are low). The main endocrine disorder of the pancreas is diabetes mellitus.
Parathyroid Glands
The parathyroid glands are located in the neck and produce parathyroid hormone (which regulates phosphate and calcium in the blood). In hyperparathyroidism there is excess parathyroid hormone which results in increased bone resorption. In hypoparathyroidism there is underproduction of parathyroid hormone resulting in low blood calcium levels.
Pineal Gland
The pineal gland is located in the brain and secretes melatonin (which helps control the body’s sleep patterns). Low melatonin levels can result in depression and sexual dysfunction.
Pituitary Gland
The pituitary gland is attached to the hypothalamus at the base of the brain. It plays a major role because it controls the activity of a number of other hormone-secreting glands. The anterior pituitary gland produces adrenocorticotropic hormone (ACTH) – responsible for stimulating the adrenal glands to secrete steroid hormones (mainly cortisol); growth hormone (GH) – responsible for regulating growth and metabolism; luteinising hormone (LH) and follicle stimulating hormone (FSH) – responsible for stimulating sex hormone production, and sperm and egg maturity; prolactin (PRL) – responsible for stimulating milk production; and thyroid stimulating hormone (TSH) – responsible for stimulating the thyroid gland to secrete thyroid hormones. The posterior pituitary gland stores anti-diuretic hormone (ADH) and oxytocin. The intermediate lobe of the pituitary gland produces melanocyte-stimulating hormone (MSH) which stimulates the production of melanin in skin cells.
Thyroid
The thyroid gland is located in the neck and produces triiodothyronine (T3) and thyroxine (T4) which regulate blood pressure, body temperature, heart rate, and metabolism. In hyperthyroidism the thyroid gland produces excessive amounts of thyroid hormone which can result in excessive sweating, weight loss, anxiety, rapid heartbeat, hand tremor and sleep problems. In hypothyroidism there is a slowing in the body’s function resulting in tiredness, weight gain, intolerance to cold temperatures, and lower heart rate. The thyroid gland also produces calcitonin which regulates calcium metabolism and strengthens bones.
Other articles in the Medical Education series:
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