← Moon Dog · Longevity Marker Guides
Optimal vs. reference ranges: why "normal" isn't the target
This explains how two kinds of ranges are defined. It does not interpret your results or tell you whether yours are fine. Only your physician can read your labs in context. Consult your doctor.
You get bloodwork back, every value is inside its range, and the portal says "normal." Yet the longevity community tracks targets that are often tighter than that range. Both can be correct at once, because a reference range and an optimal target answer two different questions.
What a reference range actually is
A lab reference range is descriptive, not aspirational. It's typically the band that the middle ~95% of a "reference population" falls into. In other words, it answers: "is this result unusual compared to other people?" If the population it was drawn from is itself trending toward metabolic or cardiovascular disease — which, for several markers, it is — then "normal" means "typical," not "low-risk."
What an optimal target is
An optimal (or "target") band answers a different question: "at what level is risk lowest, according to the outcome data?" It comes from a named author or body reading the research, and it can sit well inside — or below — the reference range. Because it's a judgment call about evidence, different authors set it differently, which is exactly why attribution matters.
Three markers where the gap is obvious
| Marker | Typical "normal" | Optimal target cited |
|---|---|---|
| Triglycerides | <150 mg/dL | <100 mg/dL |
| ApoB | often unflagged up to ~100+ mg/dL | <60 mg/dL (Attia) |
| HbA1c | <5.7% = "not diabetic" | low-5% range cited as optimal |
In each row, a result can be flagged "normal" by the lab and still be the exact number a longevity-minded person is trying to lower. The reference range isn't wrong — it's just answering "are you sick?" when the question being asked is "are you optimizing?"
This is why attribution is the whole game. An optimal target is only as trustworthy as the source behind it. "<60 mg/dL" means little on its own; "<60 mg/dL — Attia, Outlive" tells you whose judgment you're adopting and lets you check it. Unsourced "optimal" numbers are just opinions with the author filed off.
How to use the distinction
- Read both, conflate neither. Outside the reference range is a flag to discuss with a doctor. Inside the range but outside an optimal target is a goalpost, not a diagnosis.
- Track the trend, not the single dot. One value is noise; the direction over several draws is the signal.
- Know whose target you're using. If you can't name the source, you can't weigh it.
- Bring it to your physician. The targets are a framework for a conversation, not a replacement for one.
Marker shows both — your trend against a cited band
Every marker in Marker displays its optimal band with the named source attached, and plots your own values over time against it. Your result sits as a dot on a calm range, not a red "ABNORMAL" — position, never a verdict. No account, works offline, pay once.
Sources
- NCBI StatPearls — Reference ranges and how they are derived
- Peter Attia — Early and aggressive lowering of ApoB
- American Diabetes Association — Diagnosis criteria (HbA1c)
General education about how ranges are defined. Not a diagnosis, not medical advice, and not a substitute for your physician's reading of your labs.