Tip · Tracking

Annual blood test

Q: Will an annual blood test give me more years of life?

Not according to the best available evidence. The Cochrane review of 17 randomized trials with almost 252,000 participants found a risk ratio of exactly 1.00 for all-cause mortality, with a very narrow confidence interval of 0.97 to 1.03 and high certainty of evidence. No effect was seen for cancer or cardiovascular mortality either. What health checks do is find diseases earlier and control risk factors somewhat better.

Q: Why is my vitamin D level so much lower in winter?

Because at our latitudes the sun is not high enough in winter to form appreciable amounts of vitamin D in the skin. In the German examination survey, around half of adults reached 50 nmol/l or more in summer, while in winter a quarter were below 30 nmol/l. If you want to know where you stand, measure in winter or early spring.

Q: Which values are really worth it?

Those where an abnormal result has a clear consequence. Ferritin has an official threshold of below 15 micrograms per liter in healthy people and below 70 with inflammation, HbA1c has a risk gradient with a factor of 4.48 for the group between 6.0 and 6.5 percent, and vitamin D is often low and easy to correct. For thyroid and vitamin D screening in people without symptoms, on the other hand, the US Preventive Services Task Force considers the evidence insufficient.

Q: Does health insurance pay for it?

Only in part. From age 35, the statutory health check covers blood pressure, urine, blood glucose and cholesterol every three years, plus a one-time hepatitis B and C test. Vitamin D, B12, ferritin, Omega-3 Index, thyroid values and testosterone are not included and are paid for out of pocket.

Q: My testosterone is low – do I have a deficiency?

A single value is not enough for that. For a diagnosis of hypogonadism, the Endocrine Society guideline requires both matching symptoms and unequivocally and repeatedly low values, measured fasting in the morning and confirmed by a second measurement. An isolated value without symptoms is not a finding.

Q: Why is one of my values outside the reference range even though I feel fine?

Because reference ranges are constructed so that a small share of healthy people fall outside them. The more parameters you have measured at the same time, the more likely at least one abnormal value becomes, without any disease at all. That is exactly the mechanism by which screening leads to more diagnoses without lowering mortality.

What is not measured cannot be optimized.

In the biohacking scene, an annual blood test means having a broad panel measured once a year and deriving adjustments from it. The tip is here because individual markers are excellently validated against hard endpoints — and because for the overall package one of the most precise figures in preventive medicine is available.

In short

Individual values carry a lot of weight. Participants in the highest quintile of the Omega-3 Index (> 6.8 %) had a 34 % lower risk of death and a 39 % lower risk of a first cardiovascular event than those in the lowest (< 4.2 %); an HbA1c of 6.0 to below 6.5 % was associated with a hazard ratio of 4.48 for newly diagnosed diabetes. For the bundle, things look different: across 11 randomized trials with 233,298 participants, the risk ratio for all-cause mortality was exactly 1.00 (95 % CI 0.97–1.03), with high certainty of evidence. What measuring demonstrably does: find more diagnoses and control risk factors somewhat better.

What is behind it

A blood value is not an active substance but a measurement. The mechanism is therefore a causal chain: measure, detect a deficiency or an elevated risk, change something, end up better off. Each link has to be checked individually, and the chain is only as strong as its weakest link.

For some markers it is complete. According to the WHO guideline, a ferritin below 15 µg/l indicates empty iron stores, the cause can usually be found and the deficiency is treatable. For the overall package, by contrast, the chain already breaks in randomized trials: the measurement finds additional diagnoses, mortality does not change.

Which markers have been tested against hard endpoints

The Omega-3 Index is the value on the list best validated against mortality. In the Framingham Offspring cohort with 2,500 participants and a median follow-up of 7.3 years, it remained significantly associated with both endpoints after adjustment for 18 variables — total cholesterol in the same model did not. Across 10 cohorts, the hazard ratio per standard deviation higher index was 0.85 (95 % CI 0.80–0.91).

HbA1c is prognostically meaningful in non-diabetics. In 11,092 adults without diabetes, the adjusted hazard ratios for a diabetes diagnosis were 1.86 for the group 5.5 to below 6.0 % and 4.48 for 6.0 to below 6.5 %, and for coronary heart disease 1.23 and 1.78. Conversely, fasting glucose lost its significance after adjustment for HbA1c.

What a deficiency is worth

Vitamin D is the most common correctable deficiency on this list. In the nationwide examination survey of the Robert Koch Institute with 6,995 people, the mean was 45.6 nmol/l with no significant sex difference (p = 0.47); 61.6 % were below 50 nmol/l, 30.2 % below 30 nmol/l. In summer, half reached 50 nmol/l or more; in winter, 25 % were below 30 nmol/l.

Ferritin is the only value with clearly defined official thresholds. For healthy adults between 20 and 59, below 15 µg/l counts as an indication of iron deficiency, and below 70 µg/l with infection or inflammation. Above 150 µg/l in menstruating women and above 200 µg/l in men and non-menstruating women can indicate a risk of iron overload.

What is well supported

Four figures carry this page. First, the Omega-3 Index with a 34 % lower risk of death and a 39 % lower risk of a first cardiovascular event in the highest versus the lowest quintile. Second, HbA1c with a clean risk gradient from 1.86 through 4.48 to 16.47 for a diabetes diagnosis. Third, the WHO thresholds for ferritin, which turn a lab value into a decision. And fourth, just as robust, the null effect of the overall package: all-cause mortality RR 1.00 (0.97–1.03), cancer mortality RR 1.01 (0.92–1.12), cardiovascular mortality RR 1.05 (0.94–1.16), ischemic heart disease RR 0.98 (0.94–1.03). Rarely is a null result measured so narrowly.

What the studies show

Krogsbøll 2019, Cochrane

The authoritative work on the question of whether general health checks benefit people without symptoms. 17 trials included, 15 with outcome data (251,891 participants), risk of bias for the primary endpoints mostly low. All-cause mortality RR 1.00 (95 % CI 0.97–1.03; 11 trials; 233,298 participants; 21,535 deaths; high certainty of evidence, I² = 0 %). Cancer and cardiovascular mortality, ischemic heart disease and stroke also showed no effect.

Harris 2018, Journal of Clinical Lipidology

Prospective observational study in the Framingham Offspring cohort: 2,500 participants, mean age 66 years, 54 % women, median follow-up 7.3 years, 350 deaths and 245 cardiovascular events. After adjustment for 18 variables, the highest quintile of the Omega-3 Index (> 6.8 %) had a 34 % lower risk of death and a 39 % lower risk of a first cardiovascular event than the lowest (< 4.2 %).

Selvin 2010, New England Journal of Medicine

11,092 adults without diabetes and without cardiovascular disease from the ARIC study. Relative to the reference group with HbA1c 5.0 to below 5.5 %, the adjusted hazard ratios for a diabetes diagnosis were 1.86, 4.48 and 16.47 (from 6.5 %), and for coronary heart disease 1.23, 1.78 and 1.95.

Wang 2026, BMC Public Health

The broadest update, search up to July 1, 2025: 74 publications on 56 studies with more than 17 million participants. 76.9 % of the randomized trials found no significant reduction in all-cause mortality, 100 % no reduction in cardiovascular events. Diet and physical activity improved slightly; for smoking and risky alcohol consumption, 87.5 % of the studies found little or no effect.

Where the figure comes from — and where it does not

For some of the recommended markers, the responsible body explicitly considers the evidence insufficient. On vitamin D screening in asymptomatic adults, the US Preventive Services Task Force issued an I statement on April 13, 2021, and likewise in 2015 on thyroid screening in non-pregnant, asymptomatic adults. According to the Endocrine Society guideline, testosterone does not belong in routine screening. The Omega-3 Index is prognostic, not proven causal — all data come from observational cohorts. For vitamin B12, no reliable prevalence figure for German adults and no study on the benefit of routine screening could be verified.

How to do it

The statutory health check in Germany covers a one-time examination for 18- to 34-year-olds and, from age 35, one every three years with urine, blood glucose and cholesterol. Vitamin D, B12, ferritin, Omega-3 Index, thyroid values and testosterone are not included, and there is no evidence base for an annual interval. What follows from the studies: fasting in the morning if fasting glucose or testosterone is included, for testosterone with a confirmatory measurement. Measure vitamin D in winter, not in summer. Interpret ferritin together with CRP, because it is an acute-phase protein. For the Omega-3 Index, the authors consider values below 4 % the high-risk range and above 8 % the low-risk range, with a mean of 6.1 % across 10 cohorts.

Safety

The blood draw itself is low-risk — a bruise, rarely fainting. The relevant risk is the cascade that an abnormal value triggers. The Cochrane review notes that screening leads to more diagnostic and therapeutic procedures, which can harm as well as help. In the Danish Check-In study with 1,104 participants, 5 % compared with 2 % of controls received a new antidepressant within a year after a single health check (P = 0.007). Add to that the statistics of reference ranges: a value just outside is to be expected in around 5 % of healthy people. With symptoms such as persistent fatigue, weight loss, shortness of breath or blood in the stool, self-testing is the wrong route.

BK-Score Supported, with caveats

Human evidence		6
Mechanism		8
Safety data		10
Hype gap		7
Track record of use		10

For individual markers there are excellent data. For annual screening in people without symptoms, however, the benefit is disputed: large studies of general health checks found no reduction in mortality.

What is rated is the state of knowledge, not the effect. “Safety data 9” means well studied – not harmless.
Subjective assessment by Biohacking Kompakt based on published scoring rules – not a scientific rating and not a medical recommendation. Rules and all ratings (German)

Frequently asked questions about Annual blood test

Will an annual blood test give me more years of life?