Bloodwork blindspots
The last blood panel your doctor ordered for you probably included LDL, HDL, triglycerides, and total cholesterol. These three biomarkers have been part of the de facto standard panel for decades. But the standard panel has some blindspots. For example, it doesn't measure inflammation. It also doesn't measure genetics risks. Indeed - it's missing a whole lot of things that can be useful in assessing overall health and aging.

Today, we're going to focus on three biomarkers that are missing from most standard panels - yet can be powerful indicators of your health and well-being:

• Lp(a) (pronounced "L-P little a") is a cholesterol-like particle your body produces. About 1 in 5 adults has a high level, which raises heart disease and stroke risk 2 to 4 times over standard levels. Diet doesn't affect it. Exercise doesn't affect it. Standard cholesterol medications can barely change it. That's because it's primarily determined by your genetics. That's why cardiology groups in the U.S. and Canada recommend measuring it once in your life and using the answer to guide every heart health decision that follows (ACC 2018; CCS 2022). Real-world testing rate: about 1 to 2 percent (JACC Advances, 2025).
• ApoB is a protein found on every LDL particle and on other particles that can carry cholesterol into artery walls. Each particle has one ApoB, so ApoB indicates how many potentially harmful particles are in your blood. By comparison, LDL cholesterol measures how much cholesterol the LDL particles are carrying—not how many LDL particles there are. Two people can have the same LDL level but different ApoB levels. When the results differ, ApoB may provide a clearer picture of heart-disease risk. (J Clin Lipidol, 2024).
• Fasting insulin measures how much insulin your body produces before you eat. It differs from standard diabetes tests, which measure blood sugar—not insulin. Early in insulin resistance, your body produces extra insulin to keep blood sugar normal. As a result, fasting insulin may become elevated while fasting glucose and HbA1c still appear normal. This may provide an earlier opportunity to improve insulin sensitivity through sleep, exercise, nutrition, and body composition (Fiorentino et al., 2024).

Why aren't these standard?

None of these tests are new. Lp(a) has been available since the 1980s, ApoB since the late 1970s, and fasting insulin for more than 50 years.

So why aren’t they routinely tested? Cost and insurance coverage are part of the answer. Insurers tend to cover tests already included in clinical guidelines, which influences what doctors order. But coverage isn’t the only barrier. Tests also need standardized methods, clear reference ranges, and evidence that the results will change a patient’s care.

The Felix view

None of these tests are rare or particularly expensive. They're just not part of the default lab menu that most family doctors work from. If you're not sure whether your last blood work included them, you might consider joining the Longevity program, which includes all three markers – alongside a host of others.

That's the thinking behind the Felix Longevity panel. All three of these markers are on it by default, alongside the standard ones your GP already runs.

The broader point isn't about any specific test. It's about how much of longevity medicine is already sitting on a lab menu, waiting to be ordered.

TLDR: Three blood tests (Lp(a), ApoB, and fasting insulin) predict heart disease and diabetes better than the standard lipid panel does. They rarely show up on an annual physical, and they're worth knowing about.

→ Read more: Lp(a) testing trends and clinical guidance (JACC Advances, 2025)

A DEXA scan shows what BMI and a bathroom scale can’t: how much of your body is muscle versus fat, and where each is distributed. No more relying on weight alone to understand your body composition. Coming to Felix Longevity in the next few weeks

VO₂ max measures your cardiorespiratory fitness—how well your heart, lungs, and muscles work together during intense exercise. The more oxygen your body can use, the greater its capacity for sustained effort. Unlike steps or resting heart rate, VO₂ max measures what your body can do when pushed. It’s one of our most-requested additions, and it’s coming in the next few weeks.

That's it for this month's Later.

If the three tests above aren't part of the bloodwork you usually get, they're on the Felix Longevity panel by default. Something to think about the next time you're due for a check-in.

— Felix Longevity