ANA Testing: When to Tap the Brakes

This transcript has been edited for clarity. 
Hello, everybody. My name is Dr Arinola Dada. I’m a rheumatologist in the greater Seattle area. Welcome to Rheum With a Viewpoint. 
We are going to talk about that notorious (antinuclear antibody (ANA) test — when a patient comes into your office and you say, “Let’s just run a wellness check” and you order the ANA test, or the patient comes in and says, “Hey doc, order everything, okay?”
We’re going to talk about five reasons you do not want to order an ANA test without really thinking these things through. 
I’m sure you know that the ANA test, if positive, does not exclude other conditions. For instance, older women could have a positive ANA test; it’s very common in this group. 
There’s a high false-positive rate for an ANA test. For instance, cancers and viral infections can cause an ANA test to be positive, and certain medications can cause a false-positive ANA test. 
Context matters. If you have a patient that has particular symptoms, joint swelling, a strong family history of autoimmune disease, a luminal rash that you can’t understand, hair loss, those kind of things, then yes, when you order that ANA test, it’s going to be valuable. If the patient does not have those symptoms, you are just running down this rabbit hole that causes worry for you and your patient. 
The ANA test on its own is not helpful until you order the subtypes. Double-stranded DNA and anti-SSA or anti-SSB antibodies are just a few examples of the subtypes of the ANA test that really help you understand what you ordered. 
The elephant in the room: What is the pretest probability of your diagnostic test — all the symptoms, the hair loss, the malar rash, the sores in the mouth, the joint swelling, the blood in the urine? Fluid around the heart, pericarditis, pleurisy, those kinds of symptoms, right? When you have those symptoms and you order an ANA test, then you have basically put directions into your GPS. So now you know that if the test is positive, these are the things you’re going to do with the test going forward.
I hope that these five things have told you: Hey, before you order that ANA test, let’s make sure that we’re not causing unnecessary stress for our patients and also minimizing unnecessary testing. My name is Dr Arinola Dada, and thank you for listening to Rheum With a Viewpoint.