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slug: biomarkers-diagnostics
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# Biomarkers and Diagnostics

What to measure, how often, what the targets are, and how to act on a result — from at-home blood panels to clinic-level imaging (CAC, CCTA, full-body MRI, MCED). The 'measure twice, intervene once' chapter.

Start with [Comprehensive Annual Bloodwork](comprehensive-annual-bloodwork.md): a governed yearly risk review that separates useful baseline markers from testing theater. Pair it with [ApoB Screening](apob-screening.md): a particle-count view of atherogenic lipoprotein risk that explains why LDL-C alone can miss discordance. [Lp(a) Screening](lpa-screening.md) adds the once-in-adulthood inherited-risk test that can change cardiovascular-risk interpretation without becoming a repeated dashboard. [Home Blood Pressure Monitoring](blood-pressure-monitoring.md) adds the repeated out-of-office pressure signal that turns a clinic reading into a treatment-relevant pattern. [Coronary Artery Calcium Scoring](coronary-calcium-scoring.md) adds the calcified-plaque counterpart: useful when an asymptomatic cardiovascular-prevention decision is uncertain, weak as a universal screen or lifetime warranty. [Coronary CT Angiography](coronary-ct-angiography.md) adds the coronary-anatomy counterpart: useful when a clinician needs to see non-calcified plaque or stenosis, weak as routine longevity surveillance. [Continuous Glucose Monitoring (Non-Diabetic)](nondiabetic-cgm.md) adds the glucose-pattern counterpart: useful for short experiments, weak as a food verdict. [DEXA Body Composition](dexa-body-composition.md) adds the tissue-distribution counterpart, separating visceral fat, appendicular lean mass, and bone density when those measures can change a plan. [Epigenetic Age Testing](epigenetic-age-testing.md) adds the methylation-clock counterpart: useful as a model-output audit, weak as proof that a protocol changed healthy lifespan. [GDF15 as a Biomarker of Biological Aging](gdf15-aging-biomarker.md) adds the circulating cellular-stress integrator: useful as a slow-moving risk index read with the metformin and acute-illness confounds in view, weak as a target to titrate. [Resting Heart Rate and HRV](resting-hr-hrv.md) adds the wearable-era autonomic signal: useful for trends, weak as a daily command. [Full-Body MRI Screening](full-body-mri.md) is the high-cost broad-imaging entry: useful only when a scan has a pretest-risk rationale, a radiology protocol, and a follow-up rule for incidental findings. [Multi-Cancer Early Detection](mced-screening.md) adds the liquid-biopsy cancer-screening counterpart: promising for cancers without standard screening, weak as a proven annual longevity intervention. [Single-Biomarker Tunnel Vision](single-biomarker-tunnel.md) names the misuse pattern that appears when one score becomes the whole plan. The section's practical question is not how much data can be gathered, but which measurements change risk interpretation without creating testing theater.

Read straight through, or land on a specific entry and follow its outgoing links into the rest of the book.

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- [Next: ApoB Screening](apob-screening.md)
- [Previous: Exercise-Induced Hormesis](exercise-induced-hormesis.md)