8 lab tests your doctor should be doing—and 3 tests to avoid

It’s no secret that, in general, I’m not a fan of routine annual physical exams…and the battery of tests that come with them.

Even though your doctor may tell you certain tests are “recommended,” the science often doesn’t support that. And rather than detecting real problems in healthy adults, some tests are more likely to find false positives that lead to useless or even dangerous procedures—not to mention more meaningless tests.

That said, there are some lab tests that are actually useful. Meaning they’re designed for your health rather than for the convenience and profit of the clinical lab industry.

However, even with worthwhile lab tests, your doctor may not give you the complete picture in regard to your results. I’ll tell you how you can protect yourself against potentially life-threatening misinformation in just a moment.

But first, here’s a checklist of the tests your doctor should be performing on you….

Ask your doctor about these tests 

Complete blood count and a basic metabolic panel. The battery of automated blood-chemistry tests done every time you go to the doctor are, for the most part, unnecessary. But I do recommend having regular complete blood count and hemoglobin tests.

These tests can reveal if you have anemia, an infection, or possibly blood cancer.

And a basic metabolic panel measures blood levels associated with heart, liver, and kidney function, including glucose, calcium, and electrolyte levels.

Cortisol. This hormone, which is produced in your adrenal glands when you’re stressed, can be measured in your saliva. High cortisol levels can lead to weight gain; reductions in brain, bone, and muscle mass; and heart damage. Low cortisol can mean your adrenal glands are “burned out,” which can harm your immune system.

So what is the optimum cortisol level? That’s difficult to answer because your cortisol levels drop throughout the day. So if your doctor thinks your cortisol may be too high, he or she will probably test you later in the day. You’ll likely be tested in the morning if your doctor suspects your cortisol is low.

C-reactive protein (CRP). This substance, which is naturally produced in your liver, is a general marker for chronic inflammation in the body. Specifically, Highly Sensitive CRP  (Hs-CRP) tests evaluate the health of your coronary arteries, and are a much better measure of heart health than cholesterol tests.

The science varies on optimal CRP levels, so it’s best to ask your doctor about what your individual test results indicate.

Homocysteine. High levels of this amino acid are a major risk factor for heart disease, stroke, and dementia. A variety of studies show that homocysteine levels lower than 9 umol/L are optimal.

Hemoglobin A1c. A single measurement of blood sugar does not tell you all that much…and the results depend upon your last meal and fasting. But an HbA1c test tracks your average blood sugar levels over approximately four months. That makes this test important for predicting or monitoring diabetes and its complications.

A normal, healthy HbA1C level is under 6.0. (In the U.K., they say 7.0, but with a nationalized government health system, they are already well into healthcare rationing rather than actually treating patients]

Omega fatty acids. A blood test can measure the ratio of omega-3 fatty acids (from fish, seeds, and nuts) to omega-6 fatty acids (from most vegetable oils and shortening) in your cell membranes. The average ratio in Western societies is about 16 to 1 omega-6 to omega-3, but research shows that for optimum health, that ratio should be 4 to 1 or lower.1

Vitamin B12. Low levels of this nutrient are associated with anemia, fatigue, neurological disorders, and even osteoporosis. Antacids and metformin can deplete your B12 stores, so it’s also a good idea to get your levels tested if you take these drugs.

There are varying opinions on what constitutes “normal” B12 levels—anywhere from 200 to 400 ng/L or higher—so you’ll need to discuss your test results with your doctor.

Vitamin D. I know I don’t have to tell you the serious health issues that can result from a lack of this crucial vitamin, including osteoporosis, heart disease, cancer, mood disorders, and immune-system issues. A 25(OH)D test will measure the amount of vitamin D in your blood. Your levels should be in the 50-90 ng/ml range.

What your doctor may not tell you about your lab tests 

Getting the right tests from your doctor is, sadly, only half the battle. The other half has to do with how the tests are interpreted. Beware of these three key factors the next time your doctor delivers your test results.

Different definitions of “normal.” Many doctors flag only abnormal test results, often with an eye toward handing you a prescription for whatever is out of balance. But the problem is that “normal” and “abnormal” can have varying meanings based on several different factors.

For instance, “normal” blood cell counts differ between sexes and population groups. Twentieth-century medical textbooks based normal blood cell measurements on a handful of healthy, young, male medical students who just happened to be on hand when the research was conducted. But subsequent research shows that normal blood cell levels are lower in women than in men.

I also did original research during the mid-1970s, published by the World Health Organization, that showed that “normal” levels of blood cells were much lower in Asian women compared to Western women.

Age also affects blood cell count. Normal blood cell levels are lower in children and higher in adults.

And your diet, certain illicit or prescription drugs, and even some dietary supplements may cause lab results to fall outside the normal range. That’s why it’s important to tell your doctor your whole health story.

Fake findings. As I’ve written before, false-positive test results happen more often than doctors typically realize—or tell you. This is particularly true for cancer screenings. (And, of course, when it comes to cancer tests, there are also so-called “true positives” that detect conditions that aren’t really cancers at all. You might say these are true positives, but for fake cancers.)

And sometimes, you may have a disease or disorder that a test doesn’t detect. If you have symptoms or otherwise think you’re at risk for a certain medical condition, you can have any test repeated.

Different measurement criteria. Test methods and calibration can vary from one lab to another. Normal ranges are based statistically on all of the same kinds of tests done in that lab, using its instruments, on its particular patient population. So don’t be surprised when the exact same number is read as normal at one lab (and the doctor’s office that uses that lab), and abnormal at another.

(The same applies to toxicology testing in forensic medicine, which has often made for interesting expert-witness testimony.)

Also, measurements differ between countries. As I mentioned earlier, in the U.K., a HbA1c test for long-term blood glucose is considered normal if the level is below 7.0. But in the U.S., normal is under 6.0.

Vitamin D testing also presents technical challenges. First of all, the vitamin is stored in the liver but may be metabolized in the blood, so blood levels can vary. And chemically, it’s like a fat, so it doesn’t mix well with blood. There are also different forms of D that circulate in your blood. Not all lab tests measure the same forms, so there is lack of standardization. And to further complicate matters, there are two different units of measurement for vitamin D, and they’re not directly comparable.

Finally, mistakes happen. Samples get mislabeled, misplaced, and misdirected. If a test result seems questionable to you, don’t be afraid to ask for a repeat.



Think twice about these 3 tests 

Chest imaging studies. Annual chest x-rays to detect lung cancer were shown to be worthless long ago. But the government and some doctors have been shockingly slow to tell you about research conducted five years ago, as part of the half-billion-dollar National Lung Cancer Screening Trial.

Among the findings: Giving high-risk smokers and ex-smokers annual chest CAT scans would prevent a whopping 12,000 lung cancer deaths per year.

Unlike x-rays, high-resolution CAT scans can spot suspicious lung nodules…and catch lung cancer in the early, more treatable stages. So if you’re a smoker or ex-smoker, talk with your doctor about a CAT scan rather than a useless chest x-ray.

EKG. Routine EKGs are mostly a waste of time—unless you are being monitored for a known heart condition.

Lipid panel. This overblown blood cholesterol test is most often used as an excuse by doctors to prescribe more dangerous and useless statins.

Whatever the result of your lipid panel may be, it never seems to be good enough for statin-pushing cardiologists. And when it is “good enough,” big pharma gets the National Institutes of Health to change the rules for prescribing statins.

So basically, cholesterol tests are a lose-lose proposition for your health. Ask your doctor to perform CRP, homocysteine, and vitamin D tests instead to measure your heart health.



1“The importance of the ratio of omega-6/omega-3 essential fatty acids.” Biomed Pharmacother. 2002 Oct;56(8):365-79.