PhenoAge, or phenotypic age, is an estimate of biological age expressed in years, calculated from nine routine blood markers together with your chronological age. It was developed by Morgan Levine and colleagues and published in 2018. PhenoAge was fitted against mortality rather than against age itself: its inputs were chosen for separating people who died sooner from people who did not. The output is read back as an age: the age at which the measured risk profile would be unremarkable. The deeper reference entry is PhenoAge — phenotypic age.
What it measures
PhenoAge needs one standard blood draw and a date of birth. The nine inputs are albumin, creatinine, fasting glucose, C-reactive protein, lymphocyte percentage, mean cell volume, red cell distribution width, alkaline phosphatase and white blood cell count — all of them off a routine metabolic panel and a complete blood count. Each is multiplied by a weight taken from the original mortality model, combined with chronological age, and converted back into years.
Units matter more than people expect. The published equation assumes particular units, such as albumin in g/L and glucose in mmol/L, and it log-transforms C-reactive protein; a calculator fed US-lab units without conversion returns a number that looks plausible and is wrong. A separate version exists as well: DNAm PhenoAge, trained on DNA methylation to reproduce the blood-based score, part of the family described under DNAm age — epigenetic age from DNA methylation. It needs a methylation array rather than a blood panel, and the two are not interchangeable.
Typical values
PhenoAge is reported in years, so the raw figure means little on its own. What gets interpreted is the gap between it and your Chronological age, usually called PhenoAge acceleration. A negative gap means your blood chemistry resembles that of people younger than you, a positive gap means the opposite, and a gap near zero means you sit where your birth year predicts.
There is no agreed cut-off at which acceleration becomes clinically abnormal. In research it is often calculated as a residual within a specific cohort, so the same nine results can give slightly different numbers depending on the tool used. Single readings are noisy too: an infection in the week of the draw raises C-reactive protein and white cell count, and dehydration shifts albumin and creatinine. Treat one result as a snapshot, not a verdict.
Why it matters for longevity
In the cohorts where it was developed and validated, PhenoAge acceleration is associated with all-cause mortality and with cardiovascular disease, cancer and physical decline, and it carries information that chronological age alone does not. Its practical appeal is that several individually unremarkable results, each inside its own reference range, can combine into a score that is worse than average.
The evidence is observational. No trial has shown that lowering PhenoAge lowers anyone’s risk of dying, and the score moves whenever its inputs move, including for reasons that have nothing to do with aging. It summarizes risk visible in blood today; it is not a treatment target in itself.
What changes it
Several inputs respond to ordinary levers. Fasting glucose tracks diet, body weight and activity. C-reactive protein and white cell count fall when a source of chronic inflammation is treated, and rise with smoking and excess body fat. Albumin reflects protein intake, liver function and inflammation. Alkaline phosphatase responds to liver, bile and bone conditions. Red cell distribution width narrows when an iron, B12 or folate deficiency is corrected.
Others barely move on command. Creatinine follows kidney function and muscle mass, so it can rise for a good reason as well as a bad one. And the chronological age term is fixed, which is why the gap, not the score, is the part worth watching. If you retest, retest fasted, when you are well, and at the same lab.
Related reading
- What Biological Age Is and How to Measure It
- Which Blood Tests Reflect Aging and How to Read Them
- Epigenetic Clocks: Measuring Age from DNA
Disclaimer. This article is for information only and does not replace medical advice. Talk to a qualified clinician before changing anything about your health.