The Art of Diagnosis

Last week I saw a teenage boy in my office with the chief complaint of fatigue. This is a common and, because it is so vague, often frustrating compliant. Hundreds, if not thousands, of illnesses can cause fatigue and narrowing down the list of things that could be the cause can be difficult and time-consuming. It’s also frustrating because in teenagers, there are often a lot of lifestyle factors that are the cause of the fatigue (stress, poor sleep habits, early school start times, over-scheduling, poor nutrition, hormonal ups and downs, growth). It’s tricky figuring out who needs testing and who just needs to go to bed earlier.  And once we’ve decided who to test, it’s tricky figuring out what to test for.

This particular boy (let’s call him Sam) struck me as someone who needed more testing. He didn’t appear ill but he reported six months of being abnormally tired. Her reported getting a solid 8 hours of sleep a night and having a good appetite. Sam admitted to being stressed that winter as a basketball player on his high school team. He and his Mom  hadn’t been too worried about the fatigue because they had assumed it was due to stress. However, his basketball season was over and he had also quit his after school job. Those things had made his  workload much lighter but he was still fatigued. I thought about asking him to wait and see how he felt when the school year ended but something about his story made me a little more worried that there was more going on and I decided to do some basic testing.

There wasn’t anything in particular in Sam’s  history that gave clues for what could be causing his fatigue so I sent off basic bloodwork: a CBC (checking for anemia or latent infection), blood chemistries, liver function tests, thyroid tests, iron levels (looking for anemia), vitamin-D levels and antibody tests for mononucelosis.

When his labs came back I noted that he had a mildly elevated bilirubin (a substance stored in the liver), a low vitamin-D level, a high iron level and a positive mono test. The mono test wasn’t particularly useful as it was consistent with a past infection. This could have been an infection six months ago that had caused his fatigue or it could have been that Sam, like most kids, had been exposed to mono at some point in the past.  I wasn’t too worried about the bilirubin as it can sometimes be elevated from a recent virus. I wasn’t sure what to make of the high iron levels, but he wasn’t anemic which is a common cause of fatigue (although not very common in teenage boys). Vitamin-D can cause fatigue so I thought that was possibly the answer. I called Sam’s Mom and discussed the bloodwork results with her. I recommended that he start on a Vitamin-D supplement and that we could repeat the bilirubin test this summer to make sure it normalized. The tentative diagnosis was a possible recent Mono infection and Vitamin-D deficiency. I also told her about his high iron level but that I thought it was ok.

After I hung up the phone I started to wonder about that high iron level. There is a disease called hemachromatosis that is fairly rare and even more rare in children or teenagers. In this disease people absorb too much iron. Iron is essential for your body but too much is not good. It collects in the liver and in other tissues and can ultimately cause serious damage. It’s a disorder I learned about in medical school but I don’t think I’ve ever seen a real patient with it.

So, I did what anyone would do. I Googled it.  As I read about hemachromatosis and looked at Sam’s labs, I became more concerned that this could be the cause of his fatigue.

I called his Mom back and explained to her that I’d done a bit more research and that I was concerned about something called hemachromatosis. I started to explain the disease to his Mom but she stopped me. “Oh, “ she said, “My sister-in-law has that disease.” That pretty much convinced me that we had an answer.  Hemachromatosis is a genetic disease so the likelihood that Sam has it is very high when his family history is combined with his abnormal bloodwork. We sent off confirmatory bloodwork but I anticipate that it will show that he indeed has the disorder.

You could read this story as a success story for me as a diagnostician. After all, I (most likely) made the correct diagnosis in a not-straight-forward case. The other way you could look at it is how close I came to missing it. I can’t tell you exactly what made me send labs in Sam where I might not have in another teenager. Instinct? Luck? Somehow neither of those are very satisfying. I want to be sure that the next kid with fatigue who comes in will have a work-up based on something more scientific than instinct. I never elicited the key piece of information (the family history) until it was too late. How many other patients have family histories with clues in them that I don’t know?

Most importantly, I almost ignored the abnormal labwork. To a non-doctor this might seem crazy, after all why would we send bloodwork if we are going to ignore it. The truth is that every time I have ever sent labs on a patient we get something back that is abnormal. A lot of those abnormals fall under the category of “normal varient” meaning it’s really normal but just falls outside the labs range of normal. Some are lab error. Some are abnormal but will then become normal again, some temporary disturbance in the body’s physiology that isn’t really relevant. the trick is figuring out what is abnormal and needs to be pursued and what doesn’t.  We could re-test and follow-up on all these abnormals but often we then get into a situation of “chasing labs” where we forget that we are treating a real patient but are instead following some number on a piece of paper in pursuit of something normal. Pediatricians might be more reluctant to chase labs than other doctors. Our patients tend to not be so excited about getting their blood drawn so we are more reluctant to repeat a lab “just to make sure”. Ultimately, I did go back and think about Sam’s bloodwork results but I think in all honesty I could have just as easily overlooked them.

Diagnosis is tricky. It’s rarely as straightforward as non-doctors think it is. Even something like an ear infection can be open to interpretation of the physical exam. This time of year it can be tough to tell allergic rhinitis from the first day or two of a upper respiratory infection. Those aren’t life threatening conditions but the right diagnosis is still important. Another difference between doctors and non-doctors is that we don’t necessarily consider a changed diagnosis to be a failure. A typical scenario I see is a kid who comes in with a rash and either myself or one of my partners has made a diagnosis of X. A few days later the patient comes back and the rash has changed or the patient has developed new symptoms and we change the diagnosis to Y. In our minds this isn’t a mistake, we just didn’t have all the information the first time. However, I find in the mind of the parent of the patient it’s often a mis-diagnosis. After all, we were wrong the first time.

What about when we do truly fail in our diagnoses? When I look back at my own failures (and there are plenty), it’s usually that I’ve failed to take the time to listen to the patient and so I missed some critical clue in the patient’s story. Part of the reason I’ve been mulling over the process of diagnosis is that I’ve been reading Every Patient Tells a Story by Lisa Sanders.  (You knew I’d get to a book eventually, right?) In this book, Sanders explores the different ways that doctors make diagnoses: the history, the physical examination, lab tests/technology and ultimately the thinking process.

Sanders is apparently the author of a well-known column in The New York Times Magazine on medical mysteries and an advisor to the TV show House, M. D. The book jacket mentions both of these credentials and alludes to the promise of a book full of these kinds of mystery cases. Sanders does include a lot of interesting cases but she uses the cases to discuss more fully the art of diagnosis itself and how it’s changing in modern medicine. I found it a fantastic read and very thought-provoking but I’m not sure how appealing it would be to someone not in the medical world.  I would recommend it to anyone interested in medicine or who is interested in how doctors think when presented with a difficult case.

 

 

5 thoughts on “The Art of Diagnosis

  1. I enjoyed reading this, Alice, though I don’t think I have the stamina to read the book. I am an ignorant layperson when it comes to the way a doctor thinks and exactly what her work really entails. Thanks for the insight.

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  3. This is a really, really good post. Being on the listening end of the spouse of a doctor who is often answering calls, I absolutely see that medicine is “an art, not a science,” and how every patient wants a definitive diagnosis ASAP. I’d also add that it seems to me that the squishiest part of the factors going into any diagnosis is the oral history. People (myself included) simply don’t know even their own history, much less their children’s or their parents’. We misremember, we forget, and we don’t know how to connect the dots of relevant, sometimes vital information.

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