What is an internist, and why should you care?

A (long) while back, I gave you a brief explanation of what an “internist” is. I later gave you a personal view of primary care medicine and some of the challenges involved in creating an infrastructure of primary care (only 2% of American medical grads are going into primary care). We also had a little chat about medical mistakes and medical training.

No matter what changes we ultimately make in the way we train internists, one of the lessons that residency teaches is to identify who is truly sick. I don’t mean who is faking it, I mean being able to look at someone briefly and decide whether or not they need your immediate attention. It may seem obvious, but it’s not. Objective factors can sometimes be deceiving. For example, an asthmatic may have perfectly normal vital signs, including a normal oxygen level, and yet be moments away from needing a breathing machine. For an asthmatic, a normal respiratory rate may indicate fatigue rather than health, and absence of wheezing my indicate such severe airway obstruction that wheezes aren’t even possible. The ability to recognize severe illness is one of the critical goals of residency.

This is one area in which the so-called alternative medicine folks can really be dangerous.

To give you one amalgam based on far too many stories, we had a middle aged guy come on once who looked like crap. He was too thin, too weak, too pale, and too breathless. To me, it was obvious that he was seriously ill. But at a brief glance, I’m not so sure a layperson would make that same judgment. None of the individual factors was really strong enough: yes, he was pale, but so are a lot of people; yes he was thin, but maybe that’s natural for him. But when my residents and I saw him, we were fairly certain that he had TB or AIDS or cancer and that he was approaching a crisis that might kill him. We immediately admitted him to the hospital.

But that’s not what his previous health care provider did. He saw a doctor (licensed DO or MD, not sure which) who told him something about his glands not working well, and gave him supplements. When the patient got sicker, the doctor changed him to some different supplements. This isn’t only a failure of an individual doctor to recognize an individual sick patient. It is a failure of a doctor to know how to think like a doctor.

One of my professors was fond of saying that the best internist on TV was Colombo, and while that dated him a bit, the point got through. A good internist meets a patient, takes a thorough history, does a complete physical, and develops what is called a “differential diagnosis”, or a list of potential explanations for the patient’s condition. The internist then uses the data she knows to guide her to further studies, and she will cross potential diagnoses off the list as the data come in. For example, the patient above was short of breath. Physical exam did not reveal any abnormal lung or heart sounds, so pneumonia and heart failure seemed unlikely. His oxygen level was good, so lack of oxygen reaching the blood (indicating a problem likely at the level of the alveoli) seemed unlikely. A blood test showed a very low blood count. This seemed likely to be the proximate cause of his breathlessness, but for a real doctor, that’s not good enough.

The type of anemia is very important—is it from blood loss, and if so, is it acute, sub-acute, or chronic? Is it hemolytic, meaning blood cells are being destroyed? Is it due to inhibition of normal blood cell production? A good look at a blood smear can help sort this out, as can a look at additional labs. A real internist will not be satisfied giving someone “Adrenal Max” or “Energy Boost Plus”, or some such nonsense.

The reason an internist wouldn’t just give a magic potion isn’t because she doesn’t believe in magic potions (although she probably doesn’t). It’s because magic potions wouldn’t even cross her mind. It isn’t relevant to human health and disease. What is relevant is the patient, their illness, what science says is and isn’t plausible, and what medicine has found to be effective or ineffective. The doctor who gave the energy pills wasn’t right—he wasn’t even wrong. He was thinking so far outside the box, that he didn’t need to know anything about the patient or about medical science in order to prescribe the treatment. The thinking was a simplistic “energy low, give so-called energy pill”.

A friend of mine who is a lawyer was talking to me about a similar case recently and said, “why isn’t that fraud?” I didn’t have a good answer.


  1. D. C. Sessions

    Totally OT:

    Thanks. Your posts lately on the role of internists have helped me steer my mother towards getting more comprehensive care of her various age-related health issues.

  2. As far as I’m concerned, this is “Post of the Year.”

    It bored down and explained the whole ball of wax.

  3. One of my professors was fond of saying that the best internist on TV was Colombo

    Or, House?

    He’s an ass, but boy does he work those differential diagnoses!

  4. Mike Huben

    Lack of differential diagnosis sounds like one of the best arguments against CAM that I’ve heard yet. Most CAM was developed by people incapable of competent differential diagnosis, most CAM practitioners are incapable of differential diagnosis, and most CAM literature has no basis in differential diagnosis.

  5. as a side note to this post, somewhat off topic, but not entirely. my doctor…just 2 weeks ago, looked at me, and said, “if i was only looking at you, and not your medical report, i wouldnt think there is anything wrong with you!” interesting, since i have stage 1V ovarian cancer…one of the deadliest cancers at the worst stage. i feel fine! and im not complaining either. i hope and pray it stays like that!!! :). also of interest… my original pre-op scans didnt show any cancer either. they found it during surgery. i can totally see how diagnoses are difficult to make and get misdiagnosed. not that it makes it right, or anything. some things are so vague. for example…the signs of ovarian cancer are vague; which is they they call it “the silent killer”. oh…remind me to tell you my blood clot story. thats a good one too….

  6. Must resist urge to ask what final diagnosis was! Anemia is a fun workup, although maybe not so much so in this case since it sounds like it might have ended poorly. Did you get to the point of needing a bone marrow?

  7. Without making the same mistake i did last time, yes, the pt got a marrow, and underwent treatment for a hematologic malignancy that should have been diagnosed much earlier.

  8. But CAM treats the whole patient and treats them like a person!

  9. So are you going to tell us what was wrong with the guy in your story? What caused the anemia?

  10. minimalist


    But CAM treats the whole patient and treats them like a person!

    Ahaha, I was just going to post exactly that.

    Yeah, if anything gives the lie to that old CAM canard, it’s the fact that so many of their “treatments” really are based on snake oil cure-alls. Energy pills, “flushing toxins”, magic water, spinal realignment, etc. etc.

  11. I have thought “internal med” and “family practice” were interchangeable terms. Is there a significant difference?

  12. @joe

    I always thought they were the same as well…

    energy pills… meh

  13. The Blind Watchmaker

    “I have thought “internal med” and “family practice” were interchangeable terms. Is there a significant difference?”

    Yes, they are different. Internists spend their 3 years of residency learning adult medicine. They spend the majority of their time taking care of general internal medicine patients in the hospital and usually one day a week at their outpatient clinic. They also have to spend time in the sub-specialties, such as cardiology, nephrology, infectious disease, hematology/oncology and intensive care (to name a few).

    Family Practice physicians also have a 3 year residency. Again, a great deal of time is spent on the general medical floors. They spend large portions of their time in other fields like general surgery, obstetrics and pediatrics. They have a bit of a wider base of knowledge.

    Each field has its own organizations. Each has to pass separate board exams. Both are considered primary care. The internist has spent more time training in adult medicine, and (in the average internist’s opinion) may be better suited to handle complex medical issues. FP’s, on the other hand, have had a little training in medicine and can handle most of the issues. They can see children and deliver babies. In some areas, they may do minor surgeries as well.

    Internists will say they are more concentrated. Family Practitioners will say they are more broad.

    Pediatrics is a 3 year training period as well. It is analogous to Int. Med in that they spend the entire 3 years concentrating on the medical aspects of care of the child. They do not venture out into surgery or obstetrics.

    I’m sure that some FP’s, internists and pediatricians will take issue with such pigeon-holing. Between the 3 groups, there has been (friendly) rivalry.

    Hopefully, they all practice science-based medicine.

  14. The stuff about asthmatics hit home. My normal peak-flow is between 560 and 600…

    So my allergist told me to make certain that if I ever had to go to the hospital that I should make sure that the doctor knows this.

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