Blood testing provides a powerful tool to improve your mental and physical performance, reduce your future risk of chronic disease, and to increase your longevity. It is well known that blood tests are used to diagnose disease — but blood work is most powerful when used to monitor your health in a more proactive way.

Blood tests allow you to take an inside look at your body and how it functions. Getting regular blood work is the closest thing we have to x-ray vision to see inside the body. Understanding your blood biomarkers — the molecular signs of health — will help you to make more informed decisions about your diet, lifestyle, fitness, and supplement choices.

Blood work data can be used similarly to how you would use data in a business to determine if the system is functioning or failing. The proof is always in the numbers. The real power of using blood tests lies in viewing your long-term health trends. 

Your blood contains hundreds of biomarkers that can highlight the strategies that are right for your individual health, as well as identifying any underlying or developing health problems — before they turn into a full-blown crisis.

More than 70% of chronic diseases are preventable. Blood tests can help you to identify if you are at increased risk for developing a chronic disease such as heart disease, cancer, stroke, lung disease, or diabetes. Serious medical conditions can go undetected for years — without noticeable symptoms, but having regular blood tests can act as an early warning system.

It’s a long road from showing some abnormal markers to developing a full-blown chronic disease but most doctors are not looking at blood tests to define health — they’re looking at them to diagnose and treat a specific disease.

Where functional medicine differs from conventional medicine is that we aim to catch abnormalities early on that road, so that we can intervene before the patient’s health becomes dysfunctional.

“But my doctor said everything was normal”

About 50% of the patients I consult with say this to me when we first get started working together.

They know something is not normal, or their health isn’t where they want it to be — they’re experiencing symptoms they can’t explain or they just want more information about how to understand the health data they’re looking at. 

Their doctor quickly scans their blood test results during their 10-minute consult, looking for any flagged values within a wide reference range.

If they don’t see any disease patterns, they just send the patient on their way.

If nothing is specifically flagged to indicate a disease that has developed, there are no drug treatments the doctor can give you for your instinct that something is wrong.

This is a major frustration for the patient because they don’t get any information from this blood work they just did — and those results are a goldmine of information.

Most doctors are just waiting until things get to the point where they can do something about it with a drug or surgical treatment.

Here is the most important thing to know when it comes to blood testing: normal does NOT equal healthy.

‘Normal’ blood work ranges for the most common tests are often not optimal, because what’s ‘normal’ is generated by the general population of people going to that specific lab.

The normal range for a blood test is generally determined based on a bell curve of the data from those patients — many of whom are not enjoying optimal health.

A normal result from a blood test only means that you are within the range of the average population, which includes people who are sick with chronic disease, eat poorly and are overweight, and those who are sedentary.


That’s why you should be aiming for optimal, not normal, in your regular blood testing.

A much better representation of health would be to know the reference ranges of healthier populations of people with whom you can compare your data, such as those who have healthy metabolic function and no chronic disease, who take no medications, are non-smokers and exercise regularly.

As an example, here are the optimal vs. normal reference ranges for triglycerides:

A ‘normal’ reference range of fasting triglycerides is under 150 mg/dL (1.7 mmol/L).

However, a triglyceride level of over 90 mg/dL (1.02 mmol/L) may indicate poor blood sugar control and excessive carbohydrate or starch intake in the diet. 

A triglyceride level below 60 mg/dL (0.68 mmol/L) may indicate low intake of healthy dietary fat or poor digestion and absorption of fats. 

So the sweet spot, or the ‘optimal’ range, for triglycerides is between 50-90 mg/dL (0.56-1.02 mmol/L), not just anything under 150 mg/dL (1.7 mmol/L) as the lab reference range suggests.

Getting your biomarkers into optimal ranges instead of just the ‘normal’ ranges is key to slowing and preventing the development of disease, and improving your overall health.

Unfortunately, there is not an easy way to determine the optimal range for each test without compiling all the research that has ever been done on each one.

For some tests, it is good to be closer to the middle of the range, while for others it is best to be at the top or bottom end of the range.

However, you will be way ahead of most people if you simply get a comprehensive blood test each year so that you can see if there are any major changes to your historical blood data — whether or not you know the optimal ranges for each one.

If you are located in the US you can order your own blood test through Direct Labs. Click here to see my recommended annual blood tests.  

Many doctors who are trained in functional medicine have gone through the exhaustive process of researching these optimal health blood test ranges to provide a more comprehensive blood assessment to their patients.

“So when should I get my blood tested?”

Most people wait until it is too late to start monitoring their health. Waiting until you are sick is like only changing the oil in your car when the ‘check engine’ light comes on. This lack of attention to maintaining the function of your ‘car’ creates expensive future problems, such as eventual engine failure. 

Adopting a regular health monitoring strategy to stay healthy will always take less time and cost you less money than it would to deal with chronic illness after it has developed.

Most chronic diseases are preventable, and blood work allows you to ‘look under the hood,’ so that you can see into the future of your health.

With this information, you will be able to make the necessary changes now, in order to keep your body on a steady course aimed in the direction of health — rather than chronic disease.

This is because there are a lot of red flags you can see along the way before you actually develop a full-blown chronic disease. In many cases, these flags pop up years before the disease actually develops.

For example, developing type II diabetes is a many-year process, as is developing cardiovascular disease. 

With both those scenarios, you will see a progressive year-after-year trend that is still considered ‘normal’ by the lab but is still progressing in the wrong direction.

Most physicians are either not trained in identifying these patterns, or they don’t have the follow-up with patients that is necessary to notice a pattern emerging over time.

One of the most effective things you can do to optimize your health, then, is to look at your blood work each year.

If you check on your biomarkers annually, you can make sure that they’re not trending in the wrong direction, and can act quickly if you start to see something abnormal in your data. 

While there are exceptions, your doctor is most likely not doing this for you. If you’re not regularly following up with the same doctor, if you move around a lot or you don’t have a general physician who has seen you for years and years, it’s unlikely they have the information to even see that trend happening. 

It’s really something that you need to manage for yourself, because no one is going to care as much about your health as you do.

Your doctor only has time to see if something is happening right now, but until something happens, they’re just waiting. You can’t assume that your doctor is specifically looking out for you and that if something is wrong that they’re going to catch it early enough to implement a preventative treatment.

There are so many ways you can use blood work to make informed decisions about your daily health.

Blood tests can be used to determine…

The best diet and fitness routine for your body and health

Do you tend to hop from one diet to the next? Do you want to know if intermittent fasting or the Paleo diet is worth all the effort? Blood work will be your guide.

The most effective combination of supplements to achieve your health goals

Stop thinking about supplements as expensive urine and know for sure if they are worth the time and money spent.

Any areas of your health that require closer investigation

Blood work creates a window into the inner workings of your body. This window highlights the dysfunctional patterns in the body that lead to chronic disease.

When you can identify where the dysfunction is happening in your body it will become clear which diet and lifestyle changes will have the most impact.

“OK… but what about genetic, micronutrient, food intolerance, organic acid, hormone, and heavy metal tests?”

I see a lot of people who are interested in all the fancy new ways of testing and tracking their data.

Genetics is a big area of interest right now, and while those tests are great, if you don’t do the basics first with your blood work — which is a highly validated tool that has been researched and proven for decades all over the world — then the data you get from the additional tests won’t be very useful to you.

Accessing your blood work is the foundational piece of understanding your health.

There’s a place for those other tests, but getting an annual blood test is the “lowest hanging fruit” for most people to check off the list in managing their health.

Just about every decision you need to make about our health can be better informed by up-to-date blood work. 

Let’s say you have an undiagnosed thyroid problem or anemia.

Blood work will quickly highlight those problems, and give you the tools to treat them effectively. This will take care of all the symptoms that might be confused for heavy metal poisoning, for example, if you dive straight into heavy metal testing before getting a regular baseline for your blood work. 

Click the video below to see the system that I use to analyze my clients’ blood biomarker data.

How to use blood tests to determine your health

  1.  Get a comprehensive blood work assessment 1-2 times each year.
  2. Use smaller quarterly tests if you’d like to monitor the progress made from changes to your diet, fitness routine, stress management, sleep, and supplements.
  3. Compare your results each year to look for big changes in your typical blood levels.

If you are located in the US you can order your own blood test through Direct Labs. Click here to see my recommended annual blood tests. 

If you live outside of the US simply bring a list of the desired blood work tests to a local lab or hospital. Click here to see a list of labs around the world that my clients have used to successfully order their own blood tests.

Common Questions About Blood Testing

What information can I get from regular blood testing?

Blood tests will show you:

  • If you have any nutrient deficiencies increasing your chronic disease risk.
    Do you have low vitamin D that is increasing your risk of cancer and osteoporosis?
  • The dietary changes that are necessary to prevent disease and increase your mental clarity.
    Do you need to eat more healthy sources of fat or protein for optimal brain health and athletic recovery?
  • What type of fitness program is best for you.
    Do you need to incorporate high-intensity exercise or interval training?
  • What supplements will be the most effective to help you reach your health goals.
    Are your constant brain fog and low energy a result of low thyroid function or a nutrient deficiency?

Most importantly, knowing your blood work biomarkers removes the uncertainty surrounding your current state of health and will give you the peace of mind that you are taking control of your future health.

Why should I get a blood test if I am healthy?

The short answer is — to stay that way.

It is really important to get a baseline of your health when your body is functioning well. The more data that you have, the quicker you will be able to identify when dysfunction begins. It is common to see changes in blood work before the onset of symptoms.

Should I get blood testing done every year?

Yes. The real power of using blood work for the prevention of disease is viewing your long-term health trends.

Can I get blood testing done without a doctor’s order?

Yes. If you are located in the US you can order your own blood test through Direct Labs. Click here to see my recommended annual blood tests. 

If you live outside of the US simply bring a list of the desired blood work tests to a local lab or hospital. Click here to see a list of labs around the world that my clients have used to successfully order their own blood tests.

How do I know if my blood test is optimal?

There is not an easy way to determine the optimal range for each test. For some tests, it is good to be closer to the middle of the range while for others it is best to be at the top or bottom end of the range. As we saw earlier in the triglyceride example, normal and optimal are two very different things, so the best way to get the most out of your blood test is to work with a doctor who is trained in using the optimal ranges of blood work.

What does a comprehensive blood test cost?

There are now many options for getting affordable blood work.

In most areas of the world (including the US) a very comprehensive blood test is around $300-500 for 60-70 biomarkers. However, it is very easy to adjust testing to fit any budget.

Can I use insurance to get my blood tested?

It is possible to go through your local physician and use your health insurance to pay for comprehensive health blood testing. However, it is important to know that your physician may not be able or willing to order some of the tests if you do not already have a symptom or disease that supports ordering that particular test.

How often should I get my blood tested?

Most people put more thought and money into their daily coffee habit than they do to their health. Tracking your long-term blood work trends is one important way to make your health a priority.

I recommend that my clients get a comprehensive blood work assessment at least 1-2 times each year.  You can use smaller quarterly tests to help monitor the progress from changes to your diet, fitness routine, stress management, sleep, and supplements.

How do I get the most accurate blood test?

Blood testing takes a small sample of blood from one point in the circulatory system and represents how the rest of your body is operating. With such a small sample from one moment in time, there are many ways to disrupt the accuracy of your results.

9 Tips For Blood Test Success

1 – Stick to your normal routine the day before your test.

2 – Do not get your test done on a day that you feel ill unless the test is to determine why you have that specific illness.

3 – Eat a diet that is normal to you prior to your test. Do not get your testing done after a big change in your diet, such as during the holidays, after a big party, or after vacation.

4 – Make sure to follow your fasting recommendations. If your test needs to be done while fasting, schedule it for as close to 8-hours fasting as possible. Drinking water during this fasting period is ok and recommended.

5 – Do not start a new exercise routine or do a strenuous workout prior to your test.

6 – Reschedule your test if you suddenly have a poor night’s sleep and this is not a normal issue for you.

7 – Medication and supplement timing is important! For example, if you take a thyroid medication such as Levothyroxine (Synthroid) you should wait to take it until after your thyroid test. Also, the supplement Biotin can disrupt thyroid levels on the test and should be avoided for two days prior to your test.

8 – Dehydration affects your testing results. Make sure to drink at least 8 glasses of water daily prior to and the day of your test.

9 – Avoid alcohol consumption prior to your testing date.

BLOOD TESTING PRO TIP: Because the equipment and testing methods change from lab to lab, it is best to continually get your testing done from the same lab if it is possible. Comparing the results from the same lab will create the most accurate trends.

Don’t miss a health problem that could be easily identified and prevented by annual blood tests.

Checking your blood each year is a great form of health insurance that focuses on keeping you healthy, so I encourage you to find a lab in your area and book yourself a blood test today.

Part of my work with clients is to provide a comprehensive assessment of their health and blood test data.

This will help to create more clarity about their current and future health, as well as what all the tests mean. And this info can be used to make more informed health decisions.

If you are interested in a comprehensive blood work assessment and Health Program to improve your mental and physical performance, click here to review the details.

    13 replies to "How to use blood tests to improve your health"

    • Bianca

      Didn’t know that blood tests can detect a lot of what’s happening in my body. Healthy or not, it won’t hurt to get tested. And oh, I never thought normal is not always healthy. On my way to get tested!

    • Randy Chorvack

      Thank you for saying that I should get my blood tested 1-2 times a year. I just got it tested for the first time in years the other day and I was starting to wonder how often I should actually do that. I guess I’ll schedule a few appointments!

    • Lashauna Johnson

      Help Dr. Alexis I have kidney disease and I’m trying to improve my health some by my blood work can you help me please.

      • Dr. Alexis Shields

        Yes! I’d be happy to help. Please send me your contact information by going to the “Get Started” button in the right upper hand corner of my site. Talk soon.

    • Bunny C.

      Hi Dr. Shields!
      I really enjoyed your insight into the areas of health and blood work knowledge that I’ve been advocating for myself! I had blood work done two years ago with some issues I associated with possible thyroid issues and my doctor said my TCH was “normal”. Then my acupuncturist said it was high and could mean an issue. I’ve constantly (for nearly 6 years now) had a “lump in my throat” sensation right around the area where my thyroid is located… How do I advocate or ask for specific tests for hypothyroidism if my doctor thinks my levels were “normal” two years ago? What specific tests do I need to push for? Do I need to go see an ear/nose/throat doctor instead or in addition?

      Thank you!

      • Bunny C.

        *TSH, not TCH. Oops!

      • Dr. Alexis Shields

        Hi Ashley! Thank you for your question. If you are noticing a lump in the throat sensation then I recommend going back to your doctor so that they can do a physical examination of your thyroid and possible imaging. They may decide to refer you to an endocrinologist. These are the specialists who deal with thyroid function issues. A thyroid workup should include TSH, free T3, T4, free T4, and thyroid antibodies. – Dr. Alexis

    • Eli Richardson

      I’m glad you talked about the importance of checking your health with the help of medical tests. Recently, one of my uncles got a cancer scare, and we’re all worried about our health. My wife and I want to be sure we’re disease-free, so we’ll be sure to follow your advice. Thanks for the information on how to improve our life quality and its longevity.

    • rachel frampton

      My mother would like to have her blood sugar checked, which is why I told her that blood test is beneficial in monitoring matters like this. Well, you are also right that this will be able to detect any possible diseases too. Thank you for sharing here as well that this may help avoid the potential for any chronic diseases.

    • Carletta Jones

      I’m having a Metabolic blood test.
      A CBC blood work up.
      And Lipid.
      Today is Sunday….my question is this…I want to see good results from my tests. So can I get good results if I eat healthier, drink a lot if water instead of Lemon Lime soda, or eat my Enter-mans chocolate covered donuts? Is 4 days long enough to get a healthy reading? I’m 65 and I’m 5’9” and weigh 178lbs. I’m not sure why but about 3 years ago I decided that I wanted to drink lemon lime soda and pound donuts. I’m retired as of June 2022, I have only gained 3lbs, maybe 5.

    • Ashley Smith

      If my doctor isn’t worried about my numbers because they are in normal range, who then do we turn to for help guiding us to understanding our results and next steps? Nutritionist? Or are there other fields of expertise that would be a great option for helping with this?

    • Cynthia @ Activefamilychiroaz

      Regular blood tests can be a valuable tool for improving your overall health and well-being. By measuring key biomarkers such as cholesterol, blood sugar, and inflammation levels, blood tests can help identify potential health issues before they become more serious problems.

    • Krista Poper

      How long should you wait for bloodwork, so results aren’t abnormal, after indulging over vacation?

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