Using lab values to identify disease that leads to aging

Brennen McKenzie, VMD, MSc, MA, director of veterinary medicine at Loyal, a biotechnology company, and a clinical practitioner, presented an education session on lab values at the 2024 Southwest Veterinary Symposium in Fort Worth, Texas. In an interview with dvm360®, McKenzie explained how changes in lab values help identify diseases that lead to canine aging, and be used as predictors.

The following is a transcript of the video:

Brennen McKenzie, VMD, MSc, MA: [There are] a couple things that clinicians, I think, do with lab values that may be kind of problematic. One is, we get this idea of the normal range in our head. We take the reference interval and we look at it, and as long as the number is inside that box, everything's okay, and we don't have to worry about it. And I think most of us know, from some place back in our training, that the reference interval is just a statistical construct. You take a bunch of animals, you measure it [and] 95% of them fall in. That's the normal range, and that's considered okay. But it turns out that sometimes things can be outside of that range and still be normal, because 5% of the dogs had who were healthy had values outside that range. But also things can happen inside that box that are problematic, and you can see changes in trends over time that may be indicators of health problems, even though they haven't reached that cutoff threshold that we think of as normal.

What we found is that a lot of things that we often routinely measure can be associated with frailty and quality of life. So, for example, the liver enzymes, ALT and alkaline phosphatase. We measure them all the time. They're a routine part of clinical chemistry and practice, and if they're normal, we tend to ignore them. But both of those increase in dogs as they get older, and that increase is associated with declining quality of life and with an increased risk of frailty. And it may be that that's not causal. I don't think that the liver enzymes are causing those things to happen, but they're indicators. They're biomarkers. And the nice thing about that is they're easy to measure, because we measure them all the time already. So if we could find a way to use clinical lab values that we already are used to looking at in a new way as potentially predictors of problems, then that would flag certain patients for us for more intensive screening, for more aggressive therapies. You know, we would say, ‘well, hey, you know these 6 things, whatever they are, are going up in your dog, and they're still normal, but that's a bad sign that maybe something's coming in the future, and we should think about what we can do to improve weight, to improve diet, to improve exercise, to screen for diseases maybe that are subclinical.’ So that's our idea. These early associations with frailty and quality of life might be a trigger to us, and we could start paying more attention to some of these values before they hit abnormal.