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Reference · counts refreshed 2026-10-05
What each healthcare specialty and credential actually is.
49 professions and the credential letters that go with them, written in plain sentences: what the work is, how its people qualify, where they practise, and which closely related profession it is most often confused with. Every entry ends with what we hold on that population - counted from the live register, or left out when it cannot be read.
Profession family
Generalist physicians
The three specialties that take a whole patient rather than one organ or one procedure.
| Profession | What it is | On record | The list |
|---|---|---|---|
| Family medicine physician | The generalist specialty that covers every age, and how it differs from internal medicine. | 225,127 | Family medicine physicians |
| Internal medicine physician | Adult general medicine, and the classification most sub-specialties are filed beneath. | 392,894 | Internal medicine physicians |
| Pediatrician | The generalist specialty defined by age rather than by organ system. | 128,974 | Pediatricians |
Profession family
Medical specialties
Physicians who diagnose and prescribe rather than operate - most of them internists who took a further fellowship.
| Profession | What it is | On record | The list |
|---|---|---|---|
| Cardiologist | An internist with a heart and vascular fellowship, and the sub-specialties beneath it. | 36,627 | Cardiologists |
| Interventional cardiologist | Cardiology's catheter-based sub-specialty, and why it follows the cath labs. | 8,634 | Interventional cardiologists |
| Endocrinologist | Hormones, glands and metabolism - and why diabetes care reaches far beyond the specialty. | 13,105 | Endocrinologists |
| Gastroenterologist | A medical specialty with a procedure suite attached, and its own ambulatory centres. | 26,362 | Gastroenterologists |
| Hematologist-oncologist | One combined fellowship, three possible codes on the record. | 17,701 | Hematologist-oncologists |
| Medical oncologist | The systemic therapy arm of cancer care - one of three distinct oncology professions. | 6,465 | Medical oncologists |
| Nephrologist | Kidney medicine and dialysis - and not to be confused with urology. | 17,705 | Nephrologists |
| Pulmonologist | Lung medicine, usually combined with critical care - so usually a hospital specialty. | 19,895 | Pulmonologists |
| Rheumatologist | Autoimmune and inflammatory joint conditions, managed medically rather than surgically. | 10,302 | Rheumatologists |
| Infectious disease physician | A small consultative specialty with outsized say over antimicrobials and diagnostics. | 13,308 | Infectious disease physicians |
| Neurologist | Brain, spine and nerve medicine - filed on the record beside psychiatry. | 28,092 | Neurologists |
| Psychiatrist | The prescribing profession in mental health, and how it is filed on the record. | 73,381 | Psychiatrists |
| Dermatologist | Skin medicine, skin surgery and cosmetic work in one small specialty. | 27,048 | Dermatologists |
| Allergist and immunologist | One of the few fellowships entered from two different residencies. | 7,351 | Allergists and immunologists |
Profession family
Surgical specialties
Physicians who operate, and the separate classifications each surgical field is filed under.
| Profession | What it is | On record | The list |
|---|---|---|---|
| General surgeon | The broad abdominal and trauma specialty, and the classification other surgery is filed against. | 66,042 | Surgeons |
| Orthopedic surgeon | Bones, joints and spine - and the device-heavy specialty that owns its own surgery centres. | 52,880 | Orthopedic surgeons |
| Neurosurgeon | Brain and spine surgery - small, hospital-bound, and mostly spine in practice. | 12,007 | Neurosurgeons |
| Plastic surgeon | Reconstruction and cosmetic surgery - the same training, two different markets. | 9,627 | Plastic surgeons |
| Otolaryngologist (ENT) | Medical and surgical care of the ear, nose, throat, head and neck. | 19,600 | Otolaryngologists (ENT) |
| Urologist | Surgery of the urinary tract - and the specialty most often confused with nephrology. | 20,245 | Urologists |
| Obstetrician-gynecologist | Pregnancy and childbirth, plus the medical and surgical care of the reproductive system. | 77,331 | Obstetricians and gynecologists |
Profession family
Hospital-based and diagnostic specialties
The specialties whose work happens where the facility is, not where the patient lives.
| Profession | What it is | On record | The list |
|---|---|---|---|
| Anesthesiologist | Anaesthesia, pain medicine and critical care - and the care team that delivers them. | 84,793 | Anesthesiologists |
| Radiologist | The reading specialty - and the one where practice address tells you least. | 75,262 | Radiologists |
| Pathologist | Diagnosis from tissue and from the laboratory - a small population with large budgets. | 27,732 | Pathologists |
| Emergency medicine physician | The specialty of whoever comes through the door, and the staffing groups behind it. | 86,710 | Emergency medicine physicians |
Profession family
Advanced practice and nursing
Nurse practitioners, physician assistants and registered nurses - the prescribers a physician list misses.
| Profession | What it is | On record | The list |
|---|---|---|---|
| Nurse practitioner | An advanced practice nurse who diagnoses and prescribes - within the scope the state allows. | 559,076 | Nurse practitioners |
| Family nurse practitioner | The all-ages NP certification, and the largest NP population in the country. | 249,441 | Family nurse practitioners |
| Registered nurse | The largest healthcare profession, and what an identifier on the record does and does not mean. | 254,770 | Registered nurses |
| Physician assistant | A generalist-trained licensed clinician who specialises by employment, and prescribes. | 226,819 | Physician assistants |
Profession family
Dentistry
A separate profession with its own degrees, licences and specialties.
| Profession | What it is | On record | The list |
|---|---|---|---|
| Dentist | An independently licensed profession, two interchangeable degrees, nine recognised specialties. | 385,801 | Dentists |
| General dentist | Dentistry outside the recognised specialties - and where practice ownership sits. | 181,580 | General dentists |
| Orthodontist | A recognised dental specialty, usually single-specialty and multi-site. | 21,396 | Orthodontists |
| Pediatric dentist | A recognised specialty for children, concentrated in metropolitan group practice. | 17,711 | Pediatric dentists |
Profession family
Behavioural health
Who may diagnose, who may prescribe, and which licence sits behind each title.
| Profession | What it is | On record | The list |
|---|---|---|---|
| Psychologist | The doctoral behavioural health profession, and the one that does formal assessment. | 183,997 | Psychologists |
| Licensed counselor | One classification, a dozen state titles - and why this entry stops where it does. | 714,842 | Counselors |
| Clinical social worker | Therapy and the practical circumstances around it - and a very large licensed population. | 503,589 | Social workers |
Profession family
Therapy and rehabilitation
Three therapy professions and the physician specialty that directs them.
| Profession | What it is | On record | The list |
|---|---|---|---|
| Physical therapist | Movement and function, doctoral entry, and mostly clinic chains rather than individuals. | 323,798 | Physical therapists |
| Occupational therapist | The everyday-tasks profession, and why occupation does not mean employment. | 169,913 | Occupational therapists |
| Speech-language pathologist | More than speech - and a profession whose largest employer is the school system. | 219,128 | Speech-language pathologists |
| Physiatrist (PM&R) | The physician specialty of function and non-surgical musculoskeletal care. | 29,554 | Physical Medicine & Rehabilitation |
Profession family
Eye care
Two professions, and where the line between them falls.
| Profession | What it is | On record | The list |
|---|---|---|---|
| Optometrist | An independently licensed eye doctor, with scope set state by state. | 100,389 | Optometrists |
| Ophthalmologist | The surgical eye profession, and how it works alongside optometry. | 37,280 | Ophthalmologists |
Profession family
Other clinical professions
Independently licensed professions outside medicine, nursing and dentistry.
| Profession | What it is | On record | The list |
|---|---|---|---|
| Chiropractor | Manual musculoskeletal practice, portal of entry in every state, almost entirely small business. | 166,589 | Chiropractors |
| Podiatrist | A separate doctoral profession licensed to operate on the foot and ankle. | 39,253 | Podiatrists |
| Pharmacist | A doctoral profession with widening authority - and never the same thing as a pharmacy. | 332,258 | Pharmacists |
| Registered dietitian | The credentialled nutrition profession - and why nutritionist is not a reliable filter. | 79,092 | Registered dietitians |
Letters after a name
Credential letters
The letters after a name: what each degree or certification is, and what it does not tell you.
| Letters | What it is | On record | The list |
|---|---|---|---|
| MD | Doctor of Medicine - a degree, not a licence, and not a specialty. | — | — |
| DO | Doctor of Osteopathic Medicine - a full physician licence, and a growing share of the profession. | — | — |
| NP | Nurse practitioner - same credential everywhere, different scope in every state. | 559,076 | Nurse practitioners |
| PA-C | Physician assistant, certified - and the part of the abbreviation that carries information. | 226,819 | Physician assistants |
| CRNA | Certified registered nurse anesthetist - much of the anaesthesia workforce. | 80,522 | Nurse Anesthetist, Certified Registered |
| DDS | Doctor of Dental Surgery - one of two names for the same qualification. | 385,801 | Dentists |
| DMD | Doctor of Dental Medicine - a fact about the school, not about the dentist. | 385,801 | Dentists |
| DPM | Doctor of Podiatric Medicine - not an MD or DO, and licensed separately. | 39,253 | Podiatrists |
| PharmD | Doctor of Pharmacy - plus the two other sets of letters that appear beside it. | 332,258 | Pharmacists |
| LCSW | Licensed clinical social worker - the licence that allows independent therapy practice. | 503,589 | Social workers |
| PT | Physical therapist - the licence, with the doctorate usually beside it. | 323,798 | Physical therapists |
| OT | Occupational therapist - and why occupation does not mean employment. | 169,913 | Occupational therapists |
| DC | Doctor of Chiropractic - portal of entry, and no prescribing anywhere. | 166,589 | Chiropractors |
| OD | Doctor of Optometry - and the state-by-state line with eye surgery. | 100,389 | Optometrists |
How to read these pages
Reference first, product second.
A classification is not a sub-specialty
Most physician sub-specialties are filed beneath a broader classification - a cardiologist sits under internal medicine. Filtering on the classification finds the sub-specialists too; filtering on one sub-specialty code does not. How the filters combine.
Letters are filed, not verified
The credentials on a record are what the provider wrote about themselves, so MD, DO and a fellowship may appear in any combination. What somebody practises comes from the specialty codes, never from the letters, and an identifier is not a licence.
Every number here is read live
Counts come from the register at the time the page is built for you. Where a figure cannot be read it is left out rather than shown as a zero, so a missing number means exactly that and nothing worse.
Where to go for the data
Lists by specialty and state, provider search, the A to Z directory, or the API for teams that would rather not click.