What Is an Endocrinologist and What Do They Do?

An endocrinologist is a physician who specializes in endocrinology, a branch of medicine devoted to the study of diseases and disorders of hormonal glands.

The specialty involves the diagnosis and treatment of diseases that cause a deficiency or excessive production of hormones (chemical messengers like testosterone and adrenaline that coordinate different functions in the body). Examples include diabetes, thyroid disease, infertility, and polycystic ovary syndrome (PCOS).

An endocrinologist is first trained in internal medicine, pediatrics, or gynecology before specializing in endocrinology. In the United States, the typical training involves four years of college, four years of medical school, three years of residency, and two years of fellowship.

This article explains what an endocrinologist does, the types of conditions an endocrinologist treats, and what it takes to get board certification and a license to practice. It also looks at why you may need an endocrinologist and what to expect at your first appointment.

What Does an Endocrinologist Do?

Endocrinologists specialize in the diagnosis, treatment, management, and prevention of endocrine disorders. These involve infections, injuries, autoimmune diseases, genetic disorders, congenital defects, metabolic disorders, and neoplasms (benign or cancerous growth) that directly and indirectly affect the hormonal glands.

The practice of endocrinology is guided by laboratory tests more than most medical specialties. An endocrinologist is trained to interpret these findings—what they mean individually and in relationship to each other—to not only diagnose disease but to determine how to normalize hormonal imbalances based on which organ or organs are involved.

The practice also relies heavily on medical imaging and the use of contrast and radioactive dyes to evaluate the size and function of hormonal glands and detect any abnormalities. Biopsies (the extraction of tissue samples) and surgery are also facets of the practice.

Depending on the condition, an endocrinologist may work alone or with other medical professionals, including gynecologists, neurologists, oncologists, osteopathic surgeons, pediatricians, and primary care physicians.

What Makes Up the Endocrine System?

There are 10 major endocrine glands in the body that work in tandem to regulate the production and secretion of hormones in your body:

• Thyroid gland
• Parathyroid gland
• Pituitary gland
• Pineal gland
• Adrenal glands
• Thymus gland
• Testicles
• Ovaries
• Hypothalamus
• Pancreas

An endocrine disorder may involve one of these organs or a group of organs that work together as a looped system. An example includes the hypothalamic-pituitary-adrenal (HPA) axis in which the three organs respond in feedback to each other to stimulate the secretion of stress hormones like cortisol.

What Conditions Do Endocrinologists Treat?

Endocrinology encompasses a wide range of hormonal disorders affecting people of all ages and sexes, including:

• Diabetes: Such as type 1 diabetes, type 2 diabetes, and gestational diabetes
• Thyroid diseases: Such as hyperthyroidism, hypothyroidism, Grave's disease, Hashimoto's thyroiditis, and thyroid cancer
• Adrenal gland disorders: Such as Addison's disease and Cushing's disease
• Sex hormone disorders: Such as hypogonadism, amenorrhea, infertility, polycystic ovary syndrome (PCOS), precocious or delayed puberty, endometriosis, and disorders of sexual differentiation (DSD)
• Metabolic calcium and bone diseases: Such as osteoporosis, Paget's disease, hyperparathyroidism, and hyperparathyroidism
• Pituitary gland disorders: Such as Cushing's disease, pituitary adenomas, and acromegaly
  
• Systemic endocrine tumors: Such as multiple endocrine neoplasia (MEN) syndrome and carcinoid syndrome

Subspecialties

Because endocrinology is such a vast and diverse field, some endocrinologists will choose to limit their practice to specific conditions, populations, or procedures, such as:

• Diabetology (diabetes)
• Endocrine oncology (hormonal cancers)
• Endocrinology nuclear medicine
• Gender reassignment
• Neuroendocrinology
• Pediatric endocrinology
• Reproductive endocrinology (fertility specialists)
• Thyroid diseases

Training and Certification

The process of becoming an endocrinologist involves a roughly 13-year journey, starting when you obtain a four-year bachelor's degree in pre-medicine or a related field.

The journey thereafter involves:

• Medical degree: Candidates must obtain a medical degree as either a doctor of medicine (MD) or a doctor of osteopathic medicine (DO). The first two years of medical school are primarily devoted to classroom studies. The final two years involve clinical rotations in different hospitals.
• Licensure: Upon completion of medical school, graduates must pass the United States Medical Licensing Exam (USMLE) to obtain a license in the state in which they choose to practice.
• Residency: Once a license is obtained, candidates would begin their postdoctoral training by completing a three-year residency in internal medicine, pediatrics, or gynecology.
• Fellowship: Near the end of their residency, candidates would apply for a two- to three-year fellowship in endocrinology. Fellowship programs can vary, with some providing general training. while others focus on pediatrics or reproduction and infertility.
• Board certification: Endocrinologists are required to be board-certified by the American Board of Internal Medicine (ABIM). The peer-reviewed exams are comprised of written tests.

To renew a medical license, an endocrinologist must participate in continuing medical education (CME) programs and maintain a certain number of study hours. Depending on the state and medical subspecialty, licenses are renewed every seven to 10 years.

How Much Do Endocrinologists Make?

According to the annual Medscape Physician Compensation Report, endocrinologists in the United States earned a median income of $245,000 in 2022. Roughly 75% operate as private practices in a profession largely dominated by females.

Why Would I Be Referred to an Endocrinologist?

If you have been referred to an endocrinologist, it is usually because there are indications of a hormonal disorder (either through lab results or symptoms) or a diagnosed condition that is beyond the scope of practice of the referring physician. Endocrinologists are rarely your first point of contact for a medical condition and almost never work as primary care physicians.

Your primary care provider may be able to recommend an endocrinologist in your area or you search for a board-certified endocrinologist by using the ABIM verification portal.

When you first meet with an endocrinologist, you can ask whatever questions you need to better understand your condition or what may be involved in the diagnosis or treatment.

Example include:

• What experience have you had treating this condition?
• How much of your practice is devoted to this condition?
• What should I expect once I start treatment?
• What are the possible risks and complications?
• What is the success rate for the treatment?
• When might I know if the treatment is successful?
• Will the treatment affect my ability to work?
• Who do I call if there is a problem, even at night?
• Is there anything I can do to improve my condition?
• What might happen if I choose not to be treated?
• Are there any alternatives I should consider?

What to Expect at the Endocrinologist

The endocrinologist appointment usually starts with a review of your symptoms, medical history, family history, and any medications you are taking. There may also be a physical exam, particularly if there are problems with your thyroid gland, pancreas, or testicles.

Based on the initial findings, the endocrinologist will order various tests and procedures to help diagnose and/or characterize the cause of your condition. The diagnosis will direct the treatment plan.

Diagnosis

Blood and urine tests are standardly used to measure hormone levels in blood or urine samples. Other tests involve stimulating or inhibiting agents that assess how an endocrine gland reacts. In addition to blood tests, the endocrinologist may order imaging studies and other procedures to get an up-close look at a gland.

Some of the tests commonly ordered by an endocrinologist include:

• 24-hour urine collection: A urine test on which you collect all your urine throughout 24 hours provides a more accurate picture of the hormone levels in the body, including cortisol
• ACTH stimulatory test: A test that involves an injection of adrenocorticotropic hormone (ACTH) to help diagnose adrenal disorders
• Computed tomography (CT): A type of computer-assisted X-ray that creates three-dimensional "slices" of internal organs
• CRH stimulation test: A test that involves an injection of corticotropin-releasing hormone (CRH) to check for adrenal disorders
• Dexamethasone suppression test: A test that utilizes an injection of synthetic cortisol to check for Cushing's disease
• Dotatate scan: An imaging test that uses radioactive tracers to detect neuroendocrine tumors like MEN
• Fine needle aspiration (FNA) biopsy: A procedure in which a needle is inserted into the thyroid gland or tumor to extract cells for microscopic evaluation
• Magnetic resonance imaging (MRI): An imaging technique that uses powerful magnetic and radio waves to create highly detailed images of soft tissues
• Oral glucose tolerance test: A blood test that checks for diabetes after you drink a sweet glucose liquid
  
• Positron emission tomography (PET): An imaging test that uses a radioactive tracer to identify metabolic abnormalities seen in most cancers
• Radioactive iodine scan (RAI): An imaging study used to detect normal and cancerous cells in the thyroid gland
• Ultrasound: A non-invasive imaging test uses sound waves to detect masses or fluid in soft tissues
• Venous sampling: A specialized blood test involving the extraction of blood from a specific part of the body for hormone testing

Treatments

The treatments used in endocrinology are as far-ranging as the diseases involved. Many disorders can be treated with hormone replacement therapies (HRT) and other medications that normalize hormonal imbalances. Surgery and other more invasive procedures may also be needed.

Medications commonly used in endocrinology include:

• Glucocorticoids: These are manmade steroids that can normalize the function of adrenal or pituitary glands.
• Growth hormone therapy: This involves injections of growth hormone (GH) to treat growth disorders in children and GH deficiencies in adults.
• Hormonal birth control: These can be used to treat PCOs or endometriosis or to prevent osteoporosis in postmenopausal females.
• Insulin and other diabetes drugs: These oral and injected drugs can help normalize blood sugar in people with diabetes.
• Testosterone replacement: These involve injections, patches, pills, or ointment in people with hypogonadism (low testosterone).
• Thyroid replacement drugs: These include Synthroid (levothyroxine) and Cytomel (liothyronine) used to restore thyroid function in people with hypothyroidism.

Surgery and other procedures sometimes needed to treat an endocrine disorder include:

• Adrenalectomy: A surgical procedure to remove the adrenal gland in cases of cancer or Cushing's disease
• Gamma knife radiosurgery: A type of surgery utilizing beams of radiation to precisely extract tumors, including those in the hypothalamus
• Thyroidectomy: A surgical procedure to remove all or part of the thyroid gland in cases of thyroid cancer, thyroid nodules, and hyperthyroidism
• Radioiodine ablation: A technique involving an injection of radioactive iodine to destroy cancerous tissues after a thyroidectomy
  

Summary

An endocrinologist is a medical specialist trained in the diagnosis and treatment of hormonal diseases and disorders. You would be referred to an endocrinologist if you have signs or indications of a hormonal problem such as diabetes. infertility, thyroid disease, or PCOS.

It takes roughly 13 years from college through board certification to become an endocrinologist in the United States. Many endocrinologists specialize in different fields of endocrinology, including diabetes, infertility, and cancer.