Bismillah, alhamdulillah:

Doctor is my Vitamin D level low? A frequent question that many doctors are asked by their worried patients. The patient asking is worried because according to the normal values given with the lab result they are very likely to be on the lower side of the lower limit of ‘normal’.

If you are pressed for time, you can simply answer, “Yes … and you need to take this medication to correct it.”  The worried patient is satisfied with your reassuring voice and the fact that there is a simple treatment. If interested you might add that there are a plethora of studies that show that people with higher vitamin D levels have many associated advantages but carefully not mention that these are statistical correlations or based on poorly powered intervention trials.


How long do I have to take the Vitamin D for?

Satisfied the patient leaves with a prescription for Vitamin D for the next few months. Fast forward many months later … and imagine the following conversation:

Patient: Doctor how long do I have to take the Vitamin D?

Doctor: Err, you can stop now as the levels have gone up … and retest in … 6 months time.

Patient: Will my vitamin D level be okay then?

Doctor: …They are likely go down …(you answer as honestly as possible)

Patient: Does that mean I have to take the Vitamin D forever?


I will not finish that conversation but let you imagine where it may go.

Now if you have time you can go back and explain the difference between the higher clinical decision values on the lab report and the lower population-based reference values. I hear you groaning … that was a lesson in the distant past at medical school during biochemistry or was it epidemiology .. but it is difficult to remember! We don’t have time to explain all that stuff to patients, right? You might change your mind after you read the 10 finger explanation.

These reference ranges represent clinical decision values, based on the 2011 Institute of Medicine report, that apply to males and females of all ages, rather than population-based reference values

Example of a typical lab report from the Mayo Medical Lab's page on 25-Hydroxyvitamin D2 and D3, Serum


The 10 finger explanation (in under 60 seconds)

It runs like this and assumes you and your patient have all your fingers:

Doctor: Do you have a minute? I want to explain why the ‘normal’ levels are not straight forward.

Patient: Okay

Doctor: (Show your two hands and ask) How many fingers do I have?

Patient: You have ten fingers.

Doctor: (ask the patient) How many fingers do you have?

Patient: Ten

Doctor: (ask the patient) What is the normal number of fingers for a person?

Patient: Ten!

Doctor: (ask the patient) How do you know?

Patient (may pause, give them time): Because most people have ten fingers.

Doctor: (explain) Correct! If someone told that scientific studies show that with 12 fingers you can type faster and there are many advantages, would you want that?

Patient : No!

Doctor:  Okay you chose to go with ten fingers because you understood that it was normal … it was what most people had. Even if someone showed you evidence that 12 fingers are better you would not agree to have that because you understand what is normal based on what you see in most people? Correct?

Patient : That’s right.

Doctor : You just made a decision by relying on a population-based value i.e. most people have 10 fingers. You can do the same with Vitamin D. The population-based values are much lower that the ones you find printed on the lab paper. If you have no other medical complaints you can be sure that your Vitamin D is normal.

Patient: Aha! Thank you for that explanation.

The patient can now think things over and make a decision based on a better understanding of the issues involved.


I developed this simple way of explaining population-based reference values and have explained it to many patients, from various educational backgrounds in three different languages: they all get the point. It now takes me about one minute to run through that conversation.

Our patients are faced with increasing and more complex demands to ‘maintain’ their health. Sometimes the issues are straightforward and sometimes more complex. As a doctor simple tools like this are very helpful. I like to call them PICTs (Physician Information Communication Tools) sometimes its a picture, sometimes a discussion, and sometimes a demonstration with a model. The doctor is like a skilled artist, the easel is where s/he tries to paint a complex picture that helps the patient understand what is going on and help them come to a decision that they are happy with.

Let me know what you think and what response you get if you tried it.


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