Midlife labs

Decades of randomized data on the broad-spectrum annual physical converge on a sobering conclusion: routine general health checks in adults do not reduce all-cause mortality, cardiovascular events, or cancer mortality.^[1] The cost — financial, psychological, and physical — of indiscriminate testing of asymptomatic adults is real: cascades of follow-up imaging, biopsies of incidentalomas that would never have caused harm, lifelong medications started on the basis of a single borderline value. The proactive answer is not "test more"; it is to test a targeted, biologically meaningful panel and to interpret it against the ranges seen in people who actually age well — which are tighter than the population reference ranges that hospital labs print on the result.

What this page is and isn't

This is a midlife screening cadence for an otherwise healthy adult who is paying attention. It is not a workup for a specific symptom and it is not a substitute for a clinician's judgement on a particular patient. The thresholds below are the targets used in longevity-oriented practice; the headline trials that anchor each marker are linked inline, so you can see how aggressive each target actually is on evidence rather than vibes.

A useful rule of thumb running through every section: the "normal" range on a lab report is the statistical norm of a sedentary, metabolically drifting population. Optimal, in the geroscience sense, is consistently tighter — closer to the values seen in people who reach 85 in good shape than to the average 55-year-old.

The annual core panel

Six markers, drawn fasting, ideally on the same morning. Together they cover the four largest modifiable drivers of biological ageing in midlife: atherogenic lipid burden, glycaemic control and insulin sensitivity, systemic inflammation, and iron handling.

Apolipoprotein B (apoB)

For half a century cardiovascular risk has been screened on LDL cholesterol (LDL-C) — the mass of cholesterol inside LDL particles. The mechanistic driver of atherosclerosis is not cholesterol mass but the number of apoB-containing particles crossing the endothelium and lodging in the artery wall.^[2] Each atherogenic particle — LDL, VLDL, IDL, Lp(a) — carries exactly one apoB molecule, so a single apoB measurement gives a direct, standardized count.

The clinical edge of apoB over LDL-C appears in discordance: roughly a quarter of adults — disproportionately those with insulin resistance, high triglycerides, or central adiposity — have a "normal" LDL-C masking a high particle count of small, dense LDL. In those phenotypes, an LDL-driven decision underestimates real risk. The 2026 ACC/AHA dyslipidaemia guideline now explicitly recommends apoB over LDL-C as the primary lipid risk marker.

→ Full apoB-first treatment framework in Lipid management.

Fasting insulin + HbA1c (and HOMA-IR)

Standard primary care screens for type 2 diabetes use fasting glucose and HbA1c (glycated haemoglobin). Both are lagging — they only elevate after years of beta-cell stress and peripheral insulin resistance. Fasting insulin is the early-warning marker that fills the gap: as tissues become insulin-resistant, the pancreas compensates by pushing more insulin, so insulin rises before glucose budges.

A common pattern in apparently healthy 40-somethings: fasting glucose 5.3 mmol/L (95 mg/dL) — "normal"; fasting insulin 120 pmol/L (~18 μIU/mL) — quietly metabolic syndrome. Pulling the two values into the HOMA-IR index (a back-of-envelope multiplier of fasting glucose × fasting insulin) gives a single number for insulin sensitivity. HOMA-IR below 1.0 is the longevity target; above 2.0 indicates meaningful resistance even if HbA1c is in range.

The HbA1c band of 4.8–5.4% reflects centenarian cohorts and the threshold below which long-term advanced-glycation-end-product (AGE) burden stays low. Chasing a sub-4.8% HbA1c is not evidence-based and risks hypoglycaemia and frailty in older adults; aim for the band, not the floor.

High-sensitivity C-reactive protein (hs-CRP)

The most-validated circulating marker of the chronic, low-grade inflammation ("inflammaging") that underlies atherosclerosis, neurodegeneration, and several cancers. Higher hs-CRP predicts heart attacks, strokes, and all-cause mortality over 20–30-year horizons independently of LDL or apoB. The 2025 ACC scientific statement now recommends universal hs-CRP screening for primary and secondary cardiovascular prevention.^[3]

hs-CRP is an acute-phase reactant: a fresh viral infection, a hard workout in the last 24–48 hours, or a recent injury will all push it up transiently. Any elevated value should be repeated several weeks later before acting on it.

A useful systemic check: people with the highest fasting insulin have roughly fivefold higher odds of high-risk hs-CRP than those with optimal insulin sensitivity. Fixing the metabolic upstream often takes care of the inflammatory downstream without separate intervention.

Ferritin

Standard reference ranges for ferritin span from about 10 to 300+ µg/L. That range is useful for detecting severe iron-deficiency anaemia or full-blown haemochromatosis; it is not useful for midlife optimisation. Both ends of the standard "normal" carry signal:

• Low-normal ferritin (under ~30 µg/L) is the band where mitochondrial energetics, endurance, and collagen synthesis start to suffer — common in premenopausal women, distance runners, and adults on prolonged plant-based diets.
• High-normal ferritin (upper quartile of the standard range) correlates with shorter survival in older men, with elevated oxidative stress, and with metabolic syndrome — though ferritin is also an acute-phase reactant, so a high value needs to be interpreted alongside hs-CRP and a transferrin saturation panel before being called "iron overload."

If ferritin lands above target with normal hs-CRP and a transferrin saturation above 45%, that pattern points toward genuine iron loading — a hereditary haemochromatosis workup is appropriate. Why the lower-normal target matters, and the dietary levers that move it, are covered under Iron and aging.

Uric acid

Uric acid is the most mis-handled biomarker on this list because it sits on a U-shaped mortality curve — both ends elevate risk.^[4] Modest uric acid acts as an endogenous antioxidant; very low uric acid in older adults frequently reflects malnutrition or sarcopenia and correlates with higher all-cause mortality. Very high uric acid drives gout, hypertension, and metabolic syndrome.

These ranges are tighter than typical labs report; the practical use is to flag values pushing toward the edges and to interpret them in context of diet (fructose load, alcohol, purines) rather than as a stand-alone diagnosis.

Foundational organ function — CBC and CMP

A complete blood count and a comprehensive metabolic panel remain useful annual baselines despite being unsexy:

• eGFR (estimated glomerular filtration rate, on the CMP) is the single most useful renal-ageing marker. Sustained eGFR >90 mL/min/1.73 m² is the longevity target; even mild subclinical declines in filtration rate carry a disproportionate cardiovascular signal.
• ALT (alanine aminotransferase) and AST picks up early non-alcoholic fatty liver disease (NAFLD), now the most common chronic liver disorder in midlife adults and tightly tied to the insulin-resistance story above.
• CBC indices like mean corpuscular volume (MCV) and red cell distribution width (RDW) flag B12, folate, or iron problems before the more specific assays do.

Targeted micronutrients — B12 and vitamin D

Two micronutrient labs that earn their place only in defined subgroups:

• Vitamin B12 annually for adults on long-term metformin (proton-pump inhibitors and H2 blockers chronically), strict vegans, and adults over about 60 (atrophic gastritis becomes prevalent).^[5] Serum B12 alone is insensitive; confirm with methylmalonic acid (MMA) or holotranscobalamin in anything ambiguous. Target >300 pmol/L (>400 pg/mL). See B vitamins for the form and dosing detail.
• 25-hydroxyvitamin D once to establish baseline and a follow-up after dose adjustment; routine annual re-testing in already-replete adults on a stable dose adds little. See Vitamin D for the threshold-by-threshold breakdown.

The annual panel at a glance

One-time tests

A small set of markers is determined by genetics or fixed structural traits. They settle in early adulthood and don't move with diet, exercise, or standard pharmacotherapy. Drawing them more than once in a lifetime is waste.

Lp(a) — one lifetime measurement

Lipoprotein(a) is an LDL-like particle with a uniquely thrombogenic protein attached (apolipoprotein(a)). Its concentration is >90% genetically determined by variants in the LPA gene, stable for life from about age five, and unresponsive to diet, exercise, or statins (which can actually raise it modestly in some patients). Roughly 20% of the global population — over a billion adults — carries an Lp(a) high enough to materially elevate cardiovascular and aortic-valve risk.

The 2026 ACC/AHA dyslipidaemia guideline and the National Lipid Association both recommend universal one-time Lp(a) screening in every adult. The threshold for action is roughly Lp(a) >50 mg/dL or >125 nmol/L. A high result doesn't change the available drugs much in 2026 (only PCSK9 inhibitors and lipoprotein apheresis lower Lp(a); pelacarsen, lepodisiran, and muvalaplin are in late-phase trials), but it changes how aggressively the other levers are pulled — driving apoB to the lowest tolerated level, controlling blood pressure tightly, and intensifying surveillance. See Lipid management for the Lp(a)-specific drug landscape.

APOE — only as pharmacogenetics, never as predictive screening

The Apolipoprotein E ε4 allele is the largest common genetic risk factor for late-onset Alzheimer's disease and modestly elevates cardiovascular risk. The temptation to "find out your ε4 status" as a longevity test is strong; the clinical case against it is stronger.

Three reasons to refuse predictive APOE genotyping in healthy asymptomatic adults:

1. Poor discrimination. Many ε4 homozygotes never develop dementia, and most Alzheimer's patients are non-carriers. The result rarely changes individual management because the universal mitigations (aerobic exercise, sleep, blood pressure control, hearing, social engagement) apply regardless.
2. No disease-modifying prophylaxis exists for asymptomatic carriers. The result delivers anxiety without an action.
3. Insurance and disclosure risk in some jurisdictions, particularly for long-term care and disability cover.

APOE testing is clinically required in one specific context: before initiating an anti-amyloid monoclonal antibody (lecanemab, donanemab, aducanumab) in a patient with mild cognitive impairment or early Alzheimer's, because ε4 homozygotes carry a much higher risk of severe amyloid-related imaging abnormalities (ARIA) — brain oedema and microhaemorrhage — on those drugs. That is pharmacogenetic testing, not screening. The right time to draw it is at the start of an amyloid-clearing therapy decision, not at age 45 with no symptoms.

Hormones — symptom-driven, not screen-driven

Hormonal screening of asymptomatic adults is the area where direct-to-consumer "longevity" panels overreach the hardest, so the discipline here is short and firm.

• Testosterone — measure on the basis of clinical symptoms (low libido, fatigue, lost morning erections, body-composition change, persistent low mood) plus the supporting workup, not as a general "optimisation" lab. Two morning fasting draws are required because diurnal variation is large. Pursuing high-normal levels in asymptomatic men is not supported by outcome data and carries real risks (polycythaemia, exacerbation of occult prostate disease, blood-pressure elevation). See Testosterone therapy.
• Estradiol, FSH, and progesterone in women rarely give actionable information outside of symptomatic perimenopause workup, fertility evaluation, or titration of indicated menopausal hormone therapy. The decision to start MHT is symptom- and timing-driven, not lab-driven.
• TSH — the case against routine asymptomatic screening is laid out in detail in Thyroid management. The short version: a mildly elevated TSH in a well midlife adult is overwhelmingly likely to be transient or physiological, and the TRUST trial in 737 older adults showed no benefit from treating subclinical hypothyroidism on symptoms, cognition, or cardiovascular outcomes.^[6] Order TSH when there's a reason — fatigue, weight change, mood, cold intolerance, dyslipidaemia, fertility evaluation, or pregnancy.
• DHEA-S declines linearly with age, and the cortisol/DHEA-S ratio is an interesting research biomarker for adrenal resilience. As a clinical screen in healthy adults it doesn't change management; DHEA supplementation is controversial and the lab is most useful longitudinally rather than diagnostically.
• Random serum cortisol is useless as a general "stress" lab — see the tests-to-skip section below for the salivary version of the same mistake.

Biological age clocks

Where the annual panel measures the substrates of ageing, DNA-methylation-based epigenetic clocks attempt to measure ageing itself — the integrated rate at which a person's biology is drifting from their chronological age. Three generations of clocks now exist, with sharply different clinical utility:

The interesting clock for someone actively running interventions is DunedinPACE.^[7] It was trained on the Dunedin longitudinal study — a single birth cohort of New Zealanders born in 1972–1973 — by tracking 19 organ-system biomarkers across four timepoints over two decades. Because the algorithm was built within one birth year, it sidesteps the cohort confounders that plague cross-sectional clocks (leaded petrol, vaccination history, dietary environment). The output is a single number:

• 1.0 — ageing at one biological year per chronological year
• <1.0 — decelerated ageing (0.85 = 15% slower than calendar)
• >1.0 — accelerated ageing

DunedinPACE has a test-retest reliability (intraclass correlation of about 0.96) that makes it usable as a longitudinal endpoint — i.e. you can compare a result twelve months apart and the difference is more likely to reflect real biology than algorithmic noise. GrimAge remains an exceptional long-horizon mortality predictor; DunedinPACE adds incremental information about the current rate of decline, which is what someone changing diet, exercise, or pharmacology actually wants to track.

Honest caveats:

• These are surrogate biomarkers, not hard outcomes. A slowed clock under a particular intervention predicts, but doesn't prove, a longer or healthier life.
• The interventions with randomized evidence of clock slowing remain a short list — daily 1 g EPA+DHA with vitamin D and exercise in DO-HEALTH, semaglutide in HIV-lipohypertrophy, and tightly controlled caloric-restriction work. See Omega-3 and GLP-1 receptor agonists.
• The commercial clock-testing market is uneven on analytical quality. Stick to providers using validated assays (TruDiagnostic, Elysium Index, GrimAge through licensed labs) and run the same provider for serial measurements, since absolute scores aren't strictly comparable across platforms.
• Annual or twice-yearly cadence is plenty for tracking real interventions; anything more frequent samples noise.

Tests to skip

The flip side of a disciplined panel is the discipline to refuse the marketed extras. Five widely advertised tests routinely fail their own claims and reliably trigger downstream harm.

NMR LipoProfile (and other LDL-particle counts) when apoB is available

NMR spectroscopy returns an estimated LDL-P (particle number). Because every atherogenic particle carries exactly one apoB, a directly measured apoB returns the same information at a fraction of the cost — with better analytical standardisation across labs.^[8] Multiple cardiovascular outcome cohorts have shown that NMR adds essentially zero reclassification improvement over apoB. If you already have an apoB result, ordering NMR is paid-for redundancy.

Routine IGF-1 screening in healthy adults

IGF-1 is medically essential for diagnosing acromegaly and growth-hormone deficiency. As a "longevity biomarker" to be optimised in healthy adults, it fails on two counts:

1. Bidirectional risk. Cohort data show a clear U-shape — both excess and deficiency raise all-cause mortality, with low IGF-1 linked to sarcopenia and cardiovascular risk and high IGF-1 linked to cancer growth.
2. No safe modulation pathway. There is no randomized evidence that nudging IGF-1 in either direction in an asymptomatic adult improves human outcomes, and elevating it in middle age plausibly accelerates oncogenesis.

Test IGF-1 to rule in or out a pituitary disorder, not to "track ageing."

"Adrenal stress" salivary cortisol panels

"Adrenal fatigue" — the idea that chronic stress depletes cortisol output and produces a clinical syndrome — is not a recognized medical entity and has been rejected by every endocrinology society that has reviewed it.^[9] Multi-point salivary cortisol panels marketed to consumers have poor day-to-day reliability in the same individual and don't predict any defined clinical outcome.

Real disorders of the adrenal–pituitary axis (Cushing's syndrome, Addison's disease, mild autonomous cortisol secretion in adrenal incidentalomas) require specific, validated workups, not a four-tube saliva kit.

IgG (and IgG4) food-sensitivity panels

The premise — that food-specific IgG antibodies indicate intolerance — is the opposite of the immunology. Antigen-specific IgG and IgG4 represent immunological tolerance to commonly eaten foods; deliberately raising IgG4 is in fact the targeted mechanism of clinical oral immunotherapy in genuine, IgE-mediated food allergy. The American Academy of Allergy, Asthma & Immunology and the Canadian Society of Allergy and Clinical Immunology both formally advise against using IgG food panels for any clinical decision.

The downstream harm is concrete: false-positive "intolerance" results drive unnecessary elimination diets that narrow nutrition, strain social eating, and offer no symptomatic benefit on blinded re-challenge.

Provoked (post-chelation) heavy-metal urine testing

Routine screening of asymptomatic adults for heavy metals (lead, mercury, cadmium, arsenic) is already low-value unless there's an occupational or known-exposure history. The variant marketed in alternative-medicine clinics — administering a chelating agent (DMSA, DMPS) and then collecting urine — is scientifically invalid and formally condemned by the American College of Medical Toxicology.^[10]

The mechanism of the deception is straightforward: chelating agents pull trace metals out of tissue stores into the bloodstream and into urine, producing artificially high urinary metal output. The lab then compares that provoked output to the reference range for unprovoked urine, guaranteeing an "abnormal" result. The downstream pathway — months of IV chelation therapy — is expensive, nephrotoxic, and unjustified.

The harms of overtesting

The reason a disciplined panel matters isn't just cost. Every avoidable test in an asymptomatic adult carries a measurable downside:

• Overdiagnosis — finding a real biological anomaly that would never have caused harm in the patient's natural lifetime. The reference example is small, indolent papillary thyroid cancer found by high-resolution neck ultrasound; 72–94% of US diagnoses 1991–2019 were estimated to be overdiagnoses, all generating surgery, lifelong replacement therapy, and surveillance. The 2025 American Thyroid Association guidelines formally elevated active surveillance for sub-centimetre nodules in response. See Thyroid management and Cancer screening cadence.
• Cascade testing. A single ambiguous result invites confirmatory imaging, biopsies, and procedure-related complications. The base-rate problem is unforgiving: even a 95%-specific test on a 1%-prevalence finding produces more false positives than true positives.
• Iatrogenic medication starts. Borderline labs (a TSH of 5.2, an "elevated" ferritin in the upper quartile, a single high LDL on a stress week) frequently trigger lifelong prescriptions that confer no benefit and impose real side-effect burdens.
• Anxiety as a biological cost. Chronic medical anxiety is not just unpleasant — it activates the hypothalamic-pituitary-adrenal axis, elevates circulating cortisol, and drives the same inflammation pathways the patient is presumably trying to slow. A panel that produces ten "yellow lights" per year creates more biological ageing pressure than it relieves.

The asymmetry of these costs is the reason for the principle: order the smallest panel that answers a real question, and refuse the rest.

A practical annual cadence

For a generally healthy adult in midlife:

1. Annual fasting morning draw: apoB, fasting insulin, fasting glucose, HbA1c (calculate HOMA-IR from the first two), hs-CRP, ferritin (with transferrin saturation if ferritin is high), uric acid, CBC, comprehensive metabolic panel (eGFR, ALT, AST).
2. B12 annually in metformin users, vegans, adults over 60, and chronic PPI/H2-blocker users.
3. 25-hydroxyvitamin D once, with a follow-up after any dose change; not annually once stable.
4. Once-in-a-lifetime: Lp(a). Add to the first draw a midlife adult ever has. The result is permanent.
5. APOE genotype: only when an amyloid-clearing therapy decision is on the table in a patient with mild cognitive impairment.
6. Hormonal labs: symptom-driven, not screen-driven. Two morning testosterones if low-T symptoms; TSH only with corroborating signs; estradiol/FSH only in the context of perimenopause workup or MHT titration.
7. Biological-age clock — DunedinPACE annually or every two years if you are running active interventions and want a high-reliability biological endpoint.
8. Imaging and procedural screens — biennial mammography from 40 (USPSTF 2024), colorectal screening from 45 with the modality you'll actually complete, primary HPV every 5 years 30–65, low-dose CT in eligible smokers, one-time HCV antibody 18–79, one-time AAA ultrasound in men 65–75 who ever smoked. See Cancer screening cadence.
9. Refuse: NMR LipoProfile when apoB is on the panel, routine IGF-1 in healthy adults, salivary "adrenal stress" mapping, IgG/IgG4 food-sensitivity panels, and any provoked heavy-metal challenge.

Further reading

• Liss DT et al. General Health Checks in Adult Primary Care: A Review. Ann Intern Med 2021.^[11]
• Sniderman AD et al. Apolipoprotein B: Bridging the Gap Between Evidence and Clinical Practice. Circulation 2024.^[12]
• American College of Cardiology. Prioritizing Health: hsCRP as a Risk Assessment Tool — Scientific Statement. 2025.^[13]
• Mora S et al. Lipoprotein Particle Profiles by NMR Compared With Standard Lipids and Apolipoproteins in Predicting Incident CVD in Women. Circulation 2009.^[14]
• Belsky DW et al. DunedinPACE, a DNA methylation biomarker of the pace of aging. eLife 2022.^[15]
• Stott DJ et al. Thyroid Hormone Therapy for Older Adults with Subclinical Hypothyroidism (TRUST). NEJM 2017.^[16]
• Aroda VR et al. Long-term Metformin Use and Vitamin B12 Deficiency in the DPP/DPPOS. J Clin Endocrinol Metab 2016.^[17]
• Cadegiani FA, Kater CE. Adrenal fatigue does not exist: a systematic review. BMC Endocr Disord 2016.^[18]
• Charlton N et al. ACMT Position Statement: Post-Chelator Challenge Urinary Metal Testing. J Med Toxicol 2013.^[19]

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