What blood tests detect serious diseases at early stages?

Ranked on: how much serious disease each test detects at a stage where treatment changes the outcome, weighted by how common and how deadly the disease is and by the strength of the evidence for acting on the result. A test that finds disease you cannot yet treat ranks below one that finds disease you can.

1. 01

   ApoB and lipoprotein(a)

   GRADE A·EstablishedFinds the biggest killer decades early; the treatment works

   Atherosclerosis builds silently for decades and ApoB counts the particles that build it more accurately than LDL; lipoprotein(a) is a genetic risk factor that raises cardiovascular and aortic-valve risk and that nothing else detects. Order ApoB with every lipid panel and Lp(a) once in a lifetime. A high result leads to ApoB-lowering therapy with randomised mortality evidence. If you have one blood test this year, this is it.

2. 02

   HbA1c with fasting glucose and fasting insulin

   GRADE A·EstablishedCatches diabetes years before it is diabetes

   HbA1c finds established dysglycaemia; fasting insulin rises years earlier, while the pancreas is still compensating, and that is the stage at which weight, activity and diet reverse the process most reliably. Order all three annually from forty, earlier with a family history or a large waist. Act on an HbA1c of 5.7% or above and on a fasting insulin in the upper range.

3. 03

   eGFR and urine albumin-to-creatinine ratio

   GRADE A·EstablishedKidney disease is silent until late; this finds it early

   Chronic kidney disease produces no symptoms until most function is gone, and it is slowed by blood-pressure control, SGLT2 inhibitors and avoiding nephrotoxic drugs — all of which work better earlier. The urine albumin test finds damage before eGFR falls. Annually for anyone with hypertension, diabetes or a family history; every few years for everyone else.

4. 04

   Liver enzymes (ALT, AST, GGT) with a full blood count

   GRADE A·EstablishedFatty liver, alcohol damage and blood cancers show here first

   Metabolic fatty liver disease is now the commonest liver condition and is reversible early; a raised ALT is often the first sign. GGT flags alcohol. The full blood count catches anaemia, and its white-cell and platelet lines are where leukaemias and marrow disorders first appear. Cheap, annual, and I read the platelet count as carefully as the haemoglobin.

5. 05

   Ferritin (with the full blood count)

   GRADE A·EstablishedThe commonest treatable cause of fatigue, and a bleeding screen

   Low ferritin is iron deficiency long before anaemia; in a menstruating woman it is usually dietary or menstrual, and in a man or post-menopausal woman it is a reason to look for gastrointestinal blood loss — including colorectal cancer. High ferritin flags inflammation, liver disease or haemochromatosis. Pair it with hs-CRP, because inflammation inflates it.

6. 06

   TSH

   GRADE B·PromisingCommon, silent, cheap to find and treat

   Hypothyroidism mimics ageing — fatigue, weight gain, low mood, high cholesterol — and is treated with a generic tablet. Overactive thyroid causes palpitations and bone loss. One TSH every few years, or whenever symptoms suggest it; annually over sixty.

7. 07

   Hepatitis B, hepatitis C and HIV screens

   GRADE B·PromisingOnce, because all three are treatable and silent for years

   Each can run silently for a decade while damaging the liver or immune system, and each is now treatable or curable. Guidelines recommend at least one lifetime screen for adults; I would order all three once, and repeat with any risk exposure.

8. 08

   hs-CRP

   GRADE B·PromisingA risk refiner, not a disease finder

   Persistently raised hs-CRP adds to cardiovascular risk estimates and points to hidden inflammation. It spikes with any infection, so it must be repeated a month apart before acting on it. Useful alongside ApoB; not a screen on its own.

9. 09

   PSA

   GRADE C·EarlyFinds prostate cancer early — and finds cancers that would never matter

   PSA detects prostate cancer early and reduces prostate-cancer deaths modestly in trials, at the cost of many false positives, biopsies and overdiagnosed cancers that would never have caused harm. I would order it only after a conversation about that trade, generally from fifty, earlier with a family history or African ancestry.

10. 10

    p-tau217 (Alzheimer's blood test)

    GRADE C·EarlyExcellent test — for people with symptoms

    Matches amyloid PET closely and is approved for people with cognitive symptoms, where it guides diagnosis and eligibility for treatment. In a well adult it finds pathology years early with no treatment that changes the course enough to justify knowing. I would not order it as a screen.

11. 11

    Multi-cancer early detection blood tests (Galleri and similar)

    GRADE D·Insufficient or unsafeSold as early detection; detects least at early stages

    Detects about 17% of stage I cancers, so misses more than four in five at the stage that matters; the only randomised trial missed its primary endpoint; a false positive takes months and multiple scans to resolve. I would not order it until the mortality data read out, and I would not let it replace the guideline cancer screens that do have evidence.

12. 12

    Hundred-analyte 'longevity panels'

    GRADE D·Insufficient or unsafeThe dozen useful tests, buried

    Everything above is in there somewhere, alongside markers with no target, no noise band and no treatment. The extra analytes generate findings and retests, not decisions. Order the list on this page individually for a fraction of the price.