Blood tests, body scans, and imaging each reveal different layers of your health. Blood tells you what's happening biochemically. DEXA tells you about body composition and bone density. MRI reveals structural abnormalities in organs and tissues. No single test does it all — but together, they create a remarkably complete picture.
The challenge is figuring out when to use each, how often, and in what combination. Here's a practical guide to building a multi-modal testing plan.
What Each Test Type Reveals
Blood Tests
What they measure: Biochemistry — metabolic health (glucose, insulin, HbA1c), cardiovascular risk (ApoB, lipids), inflammation (hsCRP), hormones (testosterone, thyroid), organ function (liver, kidney), nutritional status (vitamins, minerals).
Strengths: Cheap, fast, repeated easily, highly responsive to interventions. The most actionable data source.
Limitations: Snapshot in time (affected by recent meals, stress, sleep). Can't detect structural abnormalities. Some important markers fluctuate significantly.
Frequency: 1–2 comprehensive panels per year, with targeted retests as needed.
DEXA Scan
What it measures: Body composition (lean mass, fat mass, visceral fat) and bone mineral density. Some DEXA centres also provide regional analysis showing fat and muscle distribution across limbs and trunk.
Strengths:
- Gold standard for body composition (more accurate than bioimpedance scales)
- Bone density assessment (osteoporosis screening)
- Visceral adipose tissue (VAT) quantification — arguably the most dangerous fat compartment
- Appendicular lean mass — the metric Attia uses to assess sarcopenia risk
Limitations: Involves a small radiation dose (minimal — equivalent to a few hours of natural background radiation). Doesn't tell you anything about organ health, vascular status, or biochemistry.
Frequency: Annually for body composition tracking, biannually for bone density.
Full Body MRI
What it measures: Structural anatomy — organs, soft tissues, brain, spine, vasculature. Detects tumours, cysts, aneurysms, degenerative changes, fatty liver, disc herniations, and more.
Strengths:
- No radiation (unlike CT)
- Excellent soft tissue contrast
- Can detect cancers, aneurysms, and organ abnormalities before symptoms appear
- Comprehensive — one scan covers head to pelvis
Limitations: Expensive. Can produce incidental findings that require follow-up. Doesn't assess coronary arteries well (need cardiac MRI or CT for that). Spatial resolution limits mean very small abnormalities may be missed.
Frequency: Every 2–3 years for screening, more often if monitoring a specific finding.
Targeted MRI Scans
For specific concerns, targeted scans offer higher resolution in a specific area:
- Cardiac MRI — Heart structure and function, myocardial fibrosis, valve assessment
- Brain MRI — Detailed neurological assessment, hippocampal volume, white matter lesions
- Liver MRI — Fatty liver quantification (MRI-PDFF), liver lesions
The Longevity Testing Timeline
| Age | Tests to Start | Rationale |
|---|---|---|
| 20s | Comprehensive blood panel, baseline Lp(a) | Establish baseline, catch early metabolic drift, know your genetic lipid risk |
| 30s | Add: annual comprehensive blood panel, DEXA every 2 years | Track body composition changes, monitor hormonal decline |
| 35+ | Add: epigenetic age testing annually | Measure pace of ageing while interventions have maximum runway |
| 40+ | Add: full body MRI every 2–3 years, cardiac MRI if risk factors | Cancer screening, aneurysm detection, structural baseline |
| 45+ | Add: colonoscopy (earlier than NHS 60+) | Colorectal cancer screening — Attia recommends starting at 40–45 |
| 50+ | Increase blood testing to 2x/year, add bone density DEXA | Hormonal changes accelerate, osteoporosis risk increases |
Putting It Together: The Annual Plan
For a 40-year-old following a longevity protocol:
| Quarter | Tests | Cost |
|---|---|---|
| Q1 (Jan–Mar) | Peak 70 blood panel | See current price |
| Q2 (Apr–Jun) | TruAge epigenetic test + DEXA | £449 |
| Q3 (Jul–Sep) | Peak 70 blood panel (retest) | See current price |
| Q4 (Oct–Dec) | Full body MRI (every 2nd or 3rd year) | Coming soon |
Start With Blood Work
The Peak 70 is the foundation of any longevity testing plan — 70 biomarkers in one test. Add imaging and epigenetic testing from there.
Order Your Peak 70 →How Blood Tests Guide Imaging Decisions
Blood work and imaging aren't independent — they inform each other:
- Elevated ALT → Liver MRI. Rising liver enzymes suggest NAFLD. MRI-PDFF quantifies liver fat percentage and can detect changes too subtle for ultrasound.
- High ApoB or Lp(a) → Cardiac MRI or CAC score. High atherogenic particle counts warrant structural cardiac assessment.
- Elevated NT-proBNP → Cardiac MRI. This cardiac stress marker should prompt detailed heart imaging.
- Low DEXA bone density → Vitamin D, calcium, hormones. Blood work identifies the underlying cause of bone loss.
- Abnormal full body MRI finding → Targeted blood tests. A suspicious liver lesion might prompt tumour markers; a thyroid nodule warrants thyroid function tests.
The testing plan isn't rigid — it evolves based on what each test reveals. Start with the foundation (blood work), add structural assessment (MRI, DEXA), and let the results guide what comes next.
At-Home Blood Testing
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