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M. Jane Wray, MD, PhD
M. Jane Wray, MD, PhD
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What is Endocrinology

What is Endocrinology?

Endocrinology is the study of hormones.  Hormones are chemicals that are present in the body in small amount but have major effects on the various functions.  To be a hormone, the substance must enter the blood at the site of production and travel to a separate site of action.  Hormones are responsible for growth, reproduction, metabolic rate, control of the blood glucose, and control of calcium.Insulin is a hormone, and that is why diabetes is also a part of endocrinology.  There are also many gastroentestinal hormones that control digestion.

The types of hormones tend to be in 2 main categories, protein and steroid.  Most of the protein hormones are small proteins called peptides. A protein is a chain of amino acids like a string of pearls. After they are made, these chains fold to bring part of the moecule called the active site together.  These hormones usally have a receptor on the cell surface to which they bind.  They effect only the cells that have the receptors.  The receptor activates and starts a cascade of events that result in changes in cell activity.  For instance growth hormone has receptors in the liver and the bone.  The liver produces a substance called Insulin Like Growth Factor 1 (IGF-1) that is also a hormone.  This hormone goes to the growth center in the bone and combined with growth hormone causes bone growth.

Steroid hormones have a stucture that resembles chicken wire.  They go to the cell nucleus and actually change the synthesis of proteins in the cell at the gene level.  Interestingly, vitamin D is also a steroid hormone, but the common name has not been changed. 

Other hormones are single or double amino acids (mono or dipeptides) such as thyroid hormone (2 tyrosines and 4 iodines) and the hormones from the center of the adrenal, adrenalins or norepinephrine which causes the fear, flight , or fight reaction such ae shaking, sweating, dry mouth, and nervousness.

The major problems with hormones are lack of production and overproduction.  This is where things really get complicated. Any endocrine gland us susceptible to autoimmune disease.  In this, the immune system somehow becomes sensitized to the gland and slowly destroys it.  The most common form of hypothyroidism (low thyroid) is autoimmune destruction of the thyroid tissue (Hashimoto's disease).

When glands are overactive, they need to be either removed or suppressed in some way.  Methimizole and PTU, for example, stop the production of thyroid hormone and are used for hyperthyroidism (high thyroid).

Endocrinology is very complicated.  Because the effects of hormone imbalance can resemble many other diseases, most of the patients an endocrinologist sees do not have an endocrine problem.  That means a lot of reassurance is given.  Endrocrinology is so interesting and challenging that it is a joy to do.  I have been so happy in this field and would not have chosen anything else.

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