What Is Endocrinology?

Endocrinology is the branch of medicine that deals with the endocrine system, which controls the hormones in your body, and the glands that produce them. Many different conditions involve the endocrine system, including diabetes, thyroid disorders, osteoporosis, growth hormone deficiency, infertility, cholesterol problems, high blood pressure, and obesity, among others.

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What Endocrinology Involves

Given that endocrinology centers on the endocrine system, let's start by looking at what it is and how it works. The endocrine system is made up of a collection of glands and organs—each with a specific role—that release hormones and work together to regulate vital functions of our body. These glands include the:

  • Thyroid
  • Hypothalamus
  • Pineal body
  • Pituitary
  • Parathyroids
  • Adrenals
  • Pancreas
  • Testes
  • Ovaries

At any given time, there are up to 40 hormones at work in the human body. They travel through the bloodstream to destinations called "targets," which can be located on various organs and tissues in the body.

It may be helpful to think of hormones as "messengers" that give instructions to different parts of the body on what to do and when to do it. There are a variety of bodily processes that involve hormones, including:

  • Blood sugar control
  • Growth and development
  • Tissue function
  • Metabolism (the process of getting and maintaining energy in the body)
  • Regulation of heart rate and blood pressure
  • Sexual development and function
  • Reproduction
  • Mood

Conditions Treated Within Endocrinology

When it comes to hormones in the body, it's all a matter of balance. And if even one of the many hormones in your body is produced at a rate that's too high or too low, it can create a hormonal imbalance and throw the rest of your body out of whack. Fortunately, the body is pretty good at regulating its hormones, and in many cases, fixes the imbalances on its own. But it's not always that straightforward.

If your primary care physician notices a hormonal imbalance in your blood work, they'll likely refer you to an endocrinologist, who can help pinpoint—or diagnose—the problem, and come up with a treatment plan.

The most common conditions and diseases within endocrinology fall into one of seven categories:

  • Diabetes
  • Thyroid
  • Adrenal
  • Parathyroid
  • Pituitary
  • Reproductive

Here are a few examples of specific conditions within each category.

Diabetes

Thyroid

  • Hyperthyroidism
  • Hypothyroidism
  • Hashimoto’s disease
  • Nodules
  • Thyroid cancer
  • Graves’ disease
  • Thyroid eye disease

Adrenal

  • Addison’s disease
  • Adrenal hyperplasia
  • Adrenal tumors
  • Pheochromocytoma: 
  • Cushing’s syndrome
  • Hyperaldosteronism

Parathyroid

  • Primary hyperparathyroidism
  • Secondary hyperparathyroidism 
  • Low blood calcium

Pituitary

  • Pituitary tumor
  • Pituitary cyst
  • Pituitary inflammation

Reproductive

Additionally, endocrinology is applicable when treating obesity, especially as it pertains to being a risk factor for type 2 diabetes, as well as osteoporosis. 

Treating Endocrine Disorders

Although there is a wide range of treatments used in managing endocrine disorders, they typically fall under three categories:

  • Hormone therapy: Supplements that restore levels of certain hormones. It also includes personalized insulin treatments for diabetes.
  • Medications: Drugs to help stop or slow the body's production of certain hormones. They may also provide relief from some of the side effects of endocrine disease, including nausea and high blood pressure.
  • Surgery: In certain circumstances, if other treatments aren't working, or if the patient has cancer, the doctor may recommend surgery to treat the affected parts of the endocrine system.

Transgender Medicine and Endocrinology

When a transgender person makes the decision to start gender-affirming hormone therapy, they work with at least one endocrinologist. Typically, doctors prescribe a combination of estrogen and androgen-lowering medications for transgender women, which may result in physical changes like enhanced breast growth, reduction of facial and body hair growth, and fat redistribution in a female pattern. For transgender men, endocrinologists give testosterone therapy for the purposes of deepening of the voice, stopping menstruation, and increasing muscle mass and facial and body hair. Whenever any type of hormone therapy is involved, doctors must discuss the potential side effects with their patients.

Training and Certification in Endocrinology

Doctors who practice endocrinology—known as endocrinologists—first must complete a three-year residency in internal medicine, followed by two to three years of fellowship training in endocrinology, diabetes, and metabolism.

It is also possible for an endocrinologist to focus on a subspecialty, like pediatric endocrinology or reproductive endocrinology and infertility.

All medical endocrinologists have an MD (or an analogous medical degree), while some also have a PhD or another advanced degree in one of the hard sciences. In order to diagnose patients, endocrinologists most frequently use laboratory testing, so many who chose this specialization have backgrounds in biochemistry and research.

History of Endocrinology

Though it's unclear exactly when elements of endocrinology were first understood, one of the first recognized references to the discipline can be found in Hippocrates' theory of the four humors (black bile, phlegm, yellow bile and blood), which dates back to around 400 B.C.E. Shortly after, Aristotle recorded specific endocrinological observations, including changes in behavior and appearance in castrated roosters. By the Middle Ages, it was thought that human organs came with special powers, so in some instances, the winners of a battle ate their enemies hearts, brains, or gonads to gain strength in related areas. But, the development of endocrinology as we know it today — much like most of modern medicine — has taken place over the last two centuries, though vast amounts of research.

A Word From Verywell

It's easy to underestimate the influence that various hormones have on our body and how it functions. They do much more than prompt puberty and oftentimes are involved with conditions like thyroid disorders that can cause confusing symptoms.

In most cases, you won't need to see an endocrinologist unless your doctor recommends it after assessing your lab results. If that happens, know that endocrinologists have specific training in the system of glands and organs that produce and regulate all the hormones we need for everyday function.

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