What is Phenotypic Age?
The research estimate of biological age from nine routine blood tests: where it comes from, what goes into it, and what it can't tell you.
Your birthday tells you your chronological age. Researchers have long tried to estimate something different: a "biological" age that reflects how your body is doing compared with others. Phenotypic Age is one of the best-known research estimates of this kind — and unusually, it can be calculated from routine blood tests many people already have.
Where it comes from
Phenotypic Age was published in 2018 by Morgan Levine and colleagues. The researchers used health data from tens of thousands of people in the United States (the NHANES surveys), including routine blood tests and many years of follow-up. They looked for the combination of measurements that best predicted mortality risk across that population, then expressed the result in years.
In simple terms, Phenotypic Age is the age at which an average person in the study population would have the same estimated risk as someone with your test results. If it's lower than your actual age, your combination of results resembles that of a younger average person in that population; if higher, an older one.
What goes into it
The calculation combines your chronological age with nine blood markers:
- Albumin
- Creatinine
- Glucose
- C-reactive protein (CRP)
- Lymphocytes (%)
- Mean cell volume (MCV)
- Red cell distribution width (RDW)
- Alkaline phosphatase
- White blood cell count
Most of these appear on common panels — a complete blood count (CBC), a metabolic panel and an inflammation marker. All nine need to come from the same blood draw for the estimate to be calculated.
The same paper also described a related measure based on DNA methylation ("DNAm PhenoAge"), which needs a specialised test. The version calculated from routine blood tests — the one discussed here — is the clinical Phenotypic Age.
What it can and can't tell you
Phenotypic Age is interesting precisely because it's built from ordinary tests. It's also easy to over-interpret. Some important limits:
- It's a statistical estimate from population data. It describes patterns across many people. It isn't a diagnosis, and it can't say anything certain about one person.
- The reference population was American. How well it applies to other populations is still being studied.
- Short-term changes move it. A cold or another infection can raise CRP and the white cell count for a while, which changes the estimate even though nothing lasting has changed.
- Units and labs matter. The formula expects specific units, and small differences between labs' methods carry through into the result.
- It's one research tool among many. Researchers continue to compare and refine different estimates of biological age.
For these reasons, a single Phenotypic Age is best treated as a curiosity, and a series over several years as a trend worth noticing — and discussing with a health professional if you have questions about it.
Phenotypic Age in SECURECORDS
When all nine markers are recorded for the same day, SECURECORDS calculates Phenotypic Age automatically — on your dashboard, for each lab visit, and in PDF reports — always labelled as a research-based estimate. It converts units carefully before calculating (the published formula uses specific units for each marker), and it shows which markers are included, so you can see where the number comes from.
Like everything in SECURECORDS, your results and the estimate are end-to-end encrypted: they're calculated on your device, and we never see them.
Source
Levine ME, Lu AT, Quach A, et al. An epigenetic biomarker of aging for lifespan and healthspan. Aging (Albany NY). 2018;10(4):573–591. doi:10.18632/aging.101414