An endocrinologist (pronounced en-də-kri-ˈnäl-ə-jist) is a medical professional who specializes in endocrinology. Endocrinology is the study of the endocrine system, which is a complex body system that regulates, produces, stores, and secretes hormones. Hormones are chemicals that affect metabolism (process of using food for energy), growth and development, sexual function and reproduction, and moods and feelings.
Endocrinologists focus on the diagnosis and treatment of metabolic disorders and other conditions that affect the endocrine system, causing abnormal hormone levels and other complications. Diabetes (also called diabetes mellitus), which results in high blood sugar levels (hyperglycemia), is the most common type of endocrine disorder.
The endocrine system helps to control many body functions and processes. It is comprised of glands and organs that secrete hormones directly into the bloodstream through the surface of the gland or organ (called "ductless"). The following glands make up the endocrine system:
- Adrenal glands (produce a number of important hormones; located on top of each kidney)
- Hypothalamus (regulates hormones that control several metabolic activities; located in the brain)
- Pancreas (produces a number of hormones and also secretes substances that aid in digestion; located behind the stomach)
- Pineal gland (produces melatonin, which is involved in the onset of puberty; located in the brain)
- Pituitary gland (secretes several hormones involved in many metabolic activities, including growth and reproduction; located in the brain)
- Reproductive glands (e.g., ovaries in women, testes in men; produce sex hormones [estrogen, testosterone] and sex cells [ova, sperm])
- Thymus gland (involved in immune system development; most of this gland is replaced by other tissue [fatty tissue, connective tissue] after puberty; located in the chest)
- Thyroid gland (produces thyroid hormone, which affects most body tissue and regulates metabolism) and parathyroid glands (regulate calcium levels), which are located in the neck
Endocrinologists diagnose metabolic disorders by performing physical examinations, laboratory tests (e.g., blood tests, urine tests), imaging tests (e.g., x-rays, ultrasound), and other diagnostic procedures. They often advise patients about preventative health measures and lifestyle changes (e.g., proper diet, regular exercise), prescribe medication (e.g., insulin, hormone therapy), and provide long-term care.
Endocrinologists often work closely with other doctors (e.g., cardiologists, oncologists) and medical professionals (e.g., pharmacists, nurses, therapists) as part of a health care team. They may work in clinics and hospitals (including teaching hospitals), in private or group practice, in health care organizations, or in the field of research (e.g., to develop new medications or treatments).
In addition to diabetes, endocrinologists also are involved in the diagnosis and treatment of the following conditions:
- Cancer of the endocrine system (e.g., adrenal cancer, thyroid cancer)
- Cardiovascular disease (heart disease)
- Growth problems
- High blood pressure (hypertension)
- High cholesterol (hypercholesterolemia; e.g., lipid disorders)
- Infertility (e.g., caused by testosterone deficiency [hypogonadism] or polycystic ovary syndrome [PCOS])
- Kidney disease
- Menopause (cessation of menstrual periods in women)
- Metabolic disorders (e.g., Addison’s disease, Cushing’s syndrome, Grave's disease, cystic fibrosis)
- Osteoporosis (bone loss that can worsen as a result of low levels of hormones, such as estrogen, testosterone, or parathyroid hormone, or long-term steroid use)
- Thyroid disorders (e.g., hyperthyroidism, hypothyroidism)
Endocrinologist Education and Training
Education and training to become an endocrinologist takes longer than 10 years to complete. Students first must obtain an undergraduate (e.g., Bachelor of Science [B.S.]) or advanced degree (e.g., Master of Science [M.S.]. Then, they must pass the Medical College Admissions Test (MCAT) and be admitted to an accredited medical school.
After completing 4 years of medical school, doctors must take and pass required written and oral examinations and obtain a medical license issued by the state in which they wish to practice. Then, medical doctors who wish to become endocrinologists enter a 3- or 4-year residency program and internship to specialize in endocrinology. These programs involve training in areas such as, internal medicine, reproductive medicine (e.g., obstetrics and gynecology), and pediatrics.
Following completion of their residency and internship, endocrinologists study the diagnosis and treatment of hormone disorders for 2 or 3 more years (called a fellowship). Endocrinologists may be board certified in endocrinology, diabetes, and metabolism by the American Board of Internal Medicine (ABIM).
Some endocrinologists specialize in certain metabolic disorders (e.g., diabetes, thyroid disease, reproductive disorders, pediatric conditions). Others work in general endocrinology or in research. Endocrine surgeons receive additional training and specialize in the surgical treatment of endocrine disorders.