Which blood biomarkers actually matter for longevity?

Short answer: several routine and some advanced blood markers track processes that strongly predict lifespan and healthspan — metabolic dysfunction, atherosclerotic risk, inflammation, kidney/liver function, nutrition status, and biological aging. Below I list the most important ones, why they matter, what direction/targets to aim for (general guidance), and how to get them tested.

Key blood biomarkers that matter for longevity

1. Glycemic/metabolic markers

• Tests: fasting glucose, HbA1c, fasting insulin, (calculate) HOMA‑IR
• Why: chronic hyperglycemia and insulin resistance drive diabetes, cardiovascular disease, cancer, and accelerated aging.
• Direction/targets (general): fasting glucose <100 mg/dL; HbA1c <5.7%; lower fasting insulin and HOMA‑IR indicate better insulin sensitivity.
• Actionable: diet, weight loss, exercise, time-restricted eating, and medications when needed.

1. Lipids and atherosclerotic risk

• Tests: LDL‑C, non‑HDL, triglycerides, HDL, ApoB, and advanced: LDL‑particle number (LDL‑P / NMR) and lipoprotein(a) Lp(a)
• Why: atherosclerotic cardiovascular disease is the biggest determinant of lifespan in most populations. ApoB or LDL‑P are better predictors than LDL‑C alone. Elevated Lp(a) is an independent genetic risk factor.
• Direction/targets (general): non‑HDL & ApoB lower is better; for general prevention LDL‑C <100 mg/dL (many longevity-oriented clinicians target <70 mg/dL if other risks). ApoB <90 mg/dL (optimal often <65). Lp(a) <50 mg/dL (or <125 nmol/L).
• Actionable: diet, exercise, statins/PCSK9/other therapies if appropriate.

1. Systemic inflammation

• Tests: high‑sensitivity CRP (hs‑CRP), IL‑6 (if available), GlycA (NMR)
• Why: chronic low‑grade inflammation (“inflammaging”) strongly predicts cardiovascular disease, frailty, dementia, and mortality.
• Direction/targets: hs‑CRP <1 mg/L desirable; 1–3 mg/L moderate; >3 mg/L high.
• Actionable: weight loss, exercise, Mediterranean-style diet, sleep, smoking cessation, treat sources of chronic inflammation/infection; medications in selected cases.

1. Kidney function

• Tests: serum creatinine → eGFR, cystatin C, urine albumin-to-creatinine ratio (ACR)
• Why: reduced kidney function predicts cardiovascular events and mortality even at mild impairment.
• Direction/targets: eGFR ≥60 mL/min/1.73 m2 ideally; lower is worse. Albuminuria even in early stages is important to address.
• Actionable: blood pressure and glucose control, ACEi/ARB as indicated, avoid nephrotoxins.

1. Cardiac stress markers (emerging risk predictors)

• Tests: NT‑proBNP, high‑sensitivity troponin (hs‑TnT or hs‑TnI)
• Why: higher levels (even within “normal” range) predict future cardiovascular events and mortality.
• Actionable: further cardiac evaluation and risk modification.

1. Liver health and metabolic toxins

• Tests: ALT, AST, GGT, albumin
• Why: nonalcoholic fatty liver disease (NAFLD) relates to metabolic dysfunction and higher mortality.
• Actionable: weight loss, metabolic control; evaluate alcohol/drug risks.

1. Hematologic markers

• Tests: hemoglobin, hematocrit, red cell distribution width (RDW)
• Why: anemia or an elevated RDW predict frailty and higher mortality across populations.
• Actionable: identify causes (iron, B12/folate, chronic disease) and treat.

1. Iron and related markers

• Tests: ferritin, transferrin saturation, serum iron
• Why: both iron deficiency and iron overload can harm health. High ferritin can reflect inflammation or iron excess.
• Actionable: adjust diet/supplements; manage hemochromatosis if present.

1. Vitamin D

• Test: 25‑hydroxyvitamin D
• Why: low levels are associated with higher mortality and several chronic diseases (evidence mixed on causality).
• Target: many clinicians aim for 25–50 ng/mL (30–50 ng/mL commonly cited).
• Actionable: sensible supplementation and recheck.

1. Thyroid function

• Tests: TSH, free T4 (and free T3 if indicated)
• Why: overt and some forms of subclinical thyroid dysfunction affect cardiovascular risk, bone health, and metabolism.
• Actionable: treat clinically significant abnormalities.

1. Sex hormones (contextual)

• Tests: total/free testosterone (men), estradiol (women as indicated), SHBG
• Why: very low or high levels (plus imbalance) relate to frailty, bone loss, and metabolic health; interpretation is age‑ and sex‑dependent.
• Actionable: evaluate by specialist; targeted therapy only when indicated.

1. Markers of biological age (advanced/optional)

• Tests/services: epigenetic clocks / DNA methylation age (e.g., TruDiagnostic, Chronomics), composite multi‑marker tests (some research labs)
• Why: these aim to estimate “biological age” and have been associated with mortality risk; still evolving clinically but useful to track interventions.
• Caveat: interpret cautiously — not diagnostic and methods differ.

How often to test

• Baseline: get a comprehensive panel once to establish a baseline.
• Routine: annually for most people; every 3–6 months if you’re actively treating a problem or changing interventions.

Where to get tested (brands/services)

• Clinical labs (for most standard tests): Quest Diagnostics, LabCorp. Why: broad test menus, reliable clinical-grade assays, widely accepted by clinicians/insurance.
• Advanced lipid/particle testing: LabCorp's NMR LipoProfile (formerly LipoScience) or Quest’s lipid options. Why: gives LDL‑P/ApoB and particle information that better predict atherosclerotic risk.
• At‑home/DTC panels (convenient for screening): Everlywell, LetsGetChecked. Why: easy sample collection, fast results — but follow up abnormal results with a clinician.
• Longevity-focused analytics + recommendations: InsideTracker, WellnessFX. Why: they combine multiple biomarkers and give lifestyle/nutrition recommendations grounded in research.
• Epigenetic aging clocks: TruDiagnostic, Chronomics (Europe), or similar. Why: dedicated methylation labs with research‑grade clocks if you want an additional “biological age” metric.
• Continuous metabolic monitoring (not a blood test but useful): NutriSense (CGM). Why: reveals glucose excursions that blood tests can miss and helps optimize metabolic health.

Caveats and next steps

• Context matters: age, sex, medications, acute illness, and labs’ reference ranges affect interpretation. Targets differ if you have existing disease.
• Don’t chase numbers without context: aim to lower overall risk with diet, activity, sleep, smoking cessation, weight control, and evidence‑based medications when needed.
• Work with a clinician: especially if you plan hormone therapy, use prescription drugs, or have abnormal results.
• Prioritize: if you can only test a few things: HbA1c (or fasting glucose), fasting lipids + ApoB, hs‑CRP, creatinine/eGFR, and 25‑OH vitamin D are a strong starting set.

If you want, tell me your age, sex, and any chronic conditions or medications and I’ll suggest a prioritized panel and realistic target ranges tailored to you.