The THREE important Rules when Ordering Diagnostic Tests for Hair Loss

To Order or Not To Order Diagnostic Tests : Three Rules Guide Whether it’s Worth it

There are three important rules when ordering or conducting a diagnostic tests. One should generally be able to answer “yes” to all three of these questions if one is going to do the test. If the answer is “no” to any of these 3 questions, one needs to seriously reconsider if ordering the given test makes sense.

The 3 questions are shown here.

QUESTION 1: Do I understand why I am ordering or performing this test? Is there good evidence to support its use?

QUESTION 2: Is there at least a reasonable chance that the result will be abnormal?

QUESTION 3: Will I ultimately do anything differently for the patient if the result returns back abnormal or normal?

Consider a 24 year old extremely healthy woman with hair loss. Should you order an ANA test just for “completeness”? That answer is no. You might say that the answer to question 1 and question 2 is yes. After all, you know why this test is done and you know that 5 % of the population has a positive ANA. Sure. But in a perfectly healthy woman with no systemic issues, ordering an ANA is not useful. Why is that? Well, even if the test result was positive, there is absolutely nothing you would do differently to the plan (step 3). No, there’s likely nothing you would do differently if the patient is perfectly healthy. The answer to step 3 is no.

Consider a 62 year old woman with classic LPP. History suggests LPP. Examination suggests LPP. Trichoscopy has never been more classic for LPP. You do not have any suspicions whatsoever for any other diagnosis besides LPP. Should you do a biopsy? Well, no. No matter what the biopsy shows, you are unlikely to do anything differently. You know it’s LPP. Doing a biopsy here is not necessarily. The answer to step 3 is “no.”

Put your favourite test to the test with these 3 simple rules!