Next from Trevor, “I’d appreciate some thoughts on lab testing on pharmaceuticals. How much will the results be affected?”
Chris: Specifically, he’s asking about someone on Inderal for heart palpitations and whether that will affect thyroid or other hormones to the point that it wouldn’t be worth testing. The answer to that question is complex because it depends on the medication, the condition, and also the information that you’re trying to obtain. For example, if you if you have a patient who’s got diabetes and they’re taking metformin and you test their blood sugar, what are you trying to know? Are you trying to know what their blood sugar is while they’re taking metformin? Well, of course in that case you would have them keep taking the metformin. Do you want to know maybe they’ve been taking it for several years that was prescribed by another clinician and you think they may not need it and it’s within your scope of practice to suggest they stop and then you want to test them without taking the metformin to see where their blood sugar is without it? I mean, that’s an obvious and simple example, but that applies in other cases.
Even some of those stool testing, you’ll often hear the lab say, “Don’t take probiotics before the test.” Well, if you want to test what their gut flora is like while they’re taking the probiotics, then the advice doesn’t make sense. You might actually want them to keep taking their probiotics when they take the test, so you can see what it’s like there.
I can’t answer that question for every different medication and situation, but that’s the way to think about it. I don’t know off the top my head how much Inderal affects thyroid test results. I can’t answer that directly.
One thing to be aware of is that high doses of biotin, like 5 mg, which is often recommended for skin, and now issues will really throw off a lot of blood tests, so make sure that your patients aren’t taking high doses of biotin when you send them to the lab for a blood draw.