Your Labs Are Normal. That Was Never the Question.

Why can my labs be normal when I do not feel normal?

Because "normal" answers a narrower question than the one you are asking. A reference range is usually built from where most of a reference population falls. A result inside it tells you that you look like most people who were tested. It does not tell you that the number is ideal for you, for your age, or for what you are about to ask your body to do.

Reference ranges were built for disease. Not for prevention, and not for optimization. That is not a criticism of your family doctor. For years there was no agreed standard for measuring how someone is aging, so a result in range was called fine and everyone moved on. We did the same.

What has changed is the toolkit. There are now validated measures of biological age, inflammation and metabolic health that can be ordered, tracked and repeated. The honest part is that they are not all equally proven, and none of them replaces a standard workup. That is why this article is specific about what each test cannot do.

Which tests are in the longevity blood panel?

Thirteen tests, sorted by the question each one helps answer. This is the full list. Most patients start with part of it.

All of these sit inside the physician-directed panels on our precision diagnostics page.

Question one

How fast am I aging? The three longevity tests

These three do not look for a single disease. They describe the terrain: how your body is aging at the cellular level, whether there is an early signal worth chasing, and whether you have the raw materials to repair.

TruAge: what is my biological age?

TruAge is an epigenetic test. It reads DNA methylation patterns from a blood sample and reports biological age alongside pace-of-aging measures such as DunedinPACE, which estimates how many biological years you are aging per calendar year.

What it cannot do. Biological age is an estimate, not a verdict, and different clocks can disagree. It works best as a longitudinal tool: the same test, repeated after a meaningful change, to see whether the number moved. We cover how to read these clocks, and their limits, in AI Moved Six Aging Clocks. Did It Reverse Aging?

Cancerguard: is there an early signal?

Cancerguard is a multi-cancer early detection blood test. One draw looks for signals associated with several cancer types, including some that have no routine screening test.

What it cannot do. It is a screening test, not a diagnosis. A positive result needs imaging and follow-up to confirm, and a negative result does not rule cancer out. It does not replace mammography, colonoscopy, cervical screening or a skin check. It is one more layer on top of them. More in our guide to cancer prevention blood testing.

NutrEval: do I have what I need to repair?

NutrEval is a functional nutrition panel that uses blood and urine to look at vitamins, minerals, amino acids, fatty acids and markers of oxidative stress. It helps answer what you are low in and what you may not be absorbing.

What it cannot do. Functional nutrition testing has less outcome evidence behind it than standard labs. We use it to direct better questions and to avoid guessing at supplements, not as a final answer.

Question two

What is quietly straining the system? Six markers of hidden stress

You can feel fine and still be under strain on the inside. Inflammation is not always a fire you can feel. These six markers are where we look for it. For the bigger picture of how internal inflammation shows up in skin, see our article on inflammation and hidden health testing.

hs-CRP: is there low-grade inflammation?

High-sensitivity C-reactive protein picks up low levels of inflammation that a standard CRP test is not designed to detect. Persistently higher levels are associated with greater cardiovascular risk.

What it cannot do. It is not specific. A cold, a hard workout, a dental infection or a recent procedure can all raise it. One elevated number means repeat it when you are well, not panic.

Omega-3 Index: what is in my cell membranes?

The Omega-3 Index measures EPA and DHA as a percentage of the fatty acids in red blood cell membranes. Because red cells live for about four months, it reflects longer-term intake, not last night's dinner.

What it cannot do. It tells you your status, not whether a supplement will change an outcome for you. It is most useful as a before-and-after measure when diet or supplementation changes.

IGF-1: how is growth hormone signalling?

IGF-1 is the main messenger of growth hormone and is involved in muscle, bone and tissue repair. It falls with age and is affected by protein intake, sleep, liver health and body composition.

What it cannot do. More is not better. Pooled studies link both low and high IGF-1 to higher mortality, so this is a marker to interpret in context, not one to push up.

Homocysteine: are the B-vitamin pathways keeping up?

Homocysteine is an amino acid that rises when B12, folate or B6 are low, and when kidney function is reduced. Higher levels are associated with a higher risk of heart disease and stroke in large observational studies.

What it cannot do. Lowering homocysteine with B vitamins has not consistently lowered cardiovascular events in trials. We read it as a signal about B-vitamin status and overall load, not as a target to treat on its own.

Free testosterone: what is actually available?

Most testosterone in the blood is bound to carrier proteins. Free testosterone is the small unbound fraction that tissues can use. The carrier protein SHBG shifts with age, weight, thyroid function and some medications, so the free fraction can be low while total testosterone looks fine.

What it cannot do. A single result is a snapshot. Levels vary through the day, so guidelines recommend a morning sample and a repeat before drawing conclusions. This applies to women as well as men, with different ranges. See the hormonal longevity guide.

Lipoprotein(a): did I inherit a risk nobody checked?

Lipoprotein(a), or Lp(a), is a cholesterol-carrying particle whose level is largely set by your genes. A high level is an independent risk factor for heart disease and aortic valve disease, and the American Heart Association estimates that roughly one in five people have one. A standard cholesterol panel does not measure it.

What it cannot do. Diet and exercise barely move it, and it is not a diagnosis of heart disease. Because it is stable through life, most people only need it measured once. We are a longevity and dermatology practice, not your cardiologist: a high Lp(a) is a result to take to one.

Question three

Which "normal" results deserve a second look?

These four are often already on your requisition. The issue is rarely that they were missed. It is that a result near the edge of the range was reported as normal and never discussed.

Ferritin: are my iron stores really adequate?

Ferritin reflects stored iron. The diagnostic line for iron deficiency has moved, and many labs still print a lower one. Ferritin also rises with inflammation, so a "normal" result can hide a low store. We go through the numbers in detail in Your Lab Says Normal. Your Hair May Disagree.

Vitamin D: is low-normal good enough?

The test is 25-hydroxyvitamin D. Results near the bottom of the range are common, especially through a Canadian winter.

The honest part. Current Endocrine Society guidance advises against routine vitamin D testing in generally healthy adults, because testing everyone has not been shown to improve outcomes. It is on this list for people with a specific reason to check, not as a number everyone needs.

Vitamin B12: is serum B12 telling the whole story?

A serum B12 result in the lower part of the range can coexist with a functional shortfall. That is why B12 is read together with homocysteine, and sometimes methylmalonic acid, in the context of symptoms. Metformin and long-term acid-suppressing medication are two common reasons levels drift down.

Total testosterone: one number, not the answer

Total testosterone counts everything in circulation, bound and unbound. It is the number most people get tested, and often the only one. On its own it can reassure falsely. You have to check free testosterone as well, which is why the two appear on this list as a pair.

How do I get reliable results?

1. Test when you are well. Illness, a recent procedure or a very hard training block can raise hs-CRP and ferritin and blur the picture.
2. Test in the morning. Testosterone is highest early in the day and guidelines call for a morning sample.
3. Tell us what you take. High-dose biotin, common in hair and nail supplements, can interfere with some lab assays. Medications matter too.
4. Repeat with the same method. A change only means something if the test, the lab and the timing are comparable.

Frequently asked questions

What blood tests should I ask for beyond a standard physical?

It depends on the question. For pace of aging: an epigenetic age test such as TruAge. For hidden inflammation and vascular risk: hs-CRP, homocysteine, lipoprotein(a) and an Omega-3 Index. For hormones: total and free testosterone and IGF-1. For results that are often normal but low: ferritin, vitamin D and B12. A physician should match the panel to your symptoms, age, sex and risk.

Why are my labs normal but I still feel tired?

A result inside the reference range means you resemble most people tested, not that the level is right for you. Fatigue with normal labs can involve low-normal ferritin, B12 or vitamin D, free testosterone that is low while total is normal, thyroid, sleep, mood, medications or inflammation. A panel is a better starting point than "you are fine", but it will not explain every case.

What is the difference between total and free testosterone?

Total testosterone measures all testosterone in the blood, most of which is bound to carrier proteins. Free testosterone is the unbound fraction available to tissues. Because the carrier protein SHBG changes with age, weight, thyroid function and medications, free testosterone can be low when total is normal. Both should be checked, on a morning sample, and repeated before decisions are made.

Is lipoprotein(a) part of a normal cholesterol test?

No. A standard lipid panel does not measure lipoprotein(a). It is a separate test, the level is largely inherited and stable through life, and most people only need it measured once. A high result should be discussed with a physician or cardiologist.

Does a multi-cancer blood test replace regular screening?

No. A multi-cancer early detection test such as Cancerguard is a screening layer, not a diagnosis. A positive result needs imaging and follow-up, a negative result does not rule out cancer, and it does not replace mammography, colonoscopy, cervical screening or skin checks.

How often should a longevity blood panel be repeated?

It depends on the test and on what changed. Inherited markers such as lipoprotein(a) are usually measured once. Markers you are trying to move are repeated after enough time for a change to register, using the same lab and method. Your physician sets the interval.

Can I get this panel if I am not in Toronto?

Consultations with Sajic Longevity are virtual. A $150 nurse consult includes SkinLife Analytics, and a $499 physician consult with Dr. Sajic includes TruAge biological age testing. The deposit is applied in full to diagnostic testing.

Sources

Guidelines and studies behind the statements above. Product names (TruAge, Cancerguard, NutrEval) refer to commercial tests from TruDiagnostic, Exact Sciences and Genova Diagnostics.

• Reyes-Soffer G, et al. Lipoprotein(a): a genetically determined, causal, and prevalent risk factor for atherosclerotic cardiovascular disease. AHA scientific statement. Arteriosclerosis, Thrombosis, and Vascular Biology. 2022.
• Pearson TA, et al. Markers of inflammation and cardiovascular disease: application to clinical and public health practice. AHA/CDC statement. Circulation. 2003.
• Homocysteine Studies Collaboration. Homocysteine and risk of ischemic heart disease and stroke: a meta-analysis. JAMA. 2002.
• Harris WS, von Schacky C. The Omega-3 Index: a new risk factor for death from coronary heart disease? Preventive Medicine. 2004.
• Burgers AMG, et al. Meta-analysis and dose-response metaregression: circulating insulin-like growth factor I (IGF-I) and mortality. Journal of Clinical Endocrinology & Metabolism. 2011.
• Bhasin S, et al. Testosterone therapy in men with hypogonadism: an Endocrine Society clinical practice guideline. Journal of Clinical Endocrinology & Metabolism. 2018.
• Demay MB, et al. Vitamin D for the prevention of disease: an Endocrine Society clinical practice guideline. Journal of Clinical Endocrinology & Metabolism. 2024.
• NICE. Vitamin B12 deficiency in over 16s: diagnosis and management (NG239). 2024.
• Belsky DW, et al. DunedinPACE, a DNA methylation biomarker of the pace of aging. eLife. 2022.