There are four essential lab tests that can be run by your conventional doctor in order to uncover the cause of your fatigue.
The conventional treatment of chronic fatigue syndrome is wretched. Antidepressants and painkillers are never going to address the underlying or root cause of your fatigue. But before you spend lots of money on a functional medicine practitioner, have your conventional doctor run the following lab tests. These labs are some of the more common causes of fatigue. Unfortunately, even they are seldom tested for in a conventional setting.
Your chronic fatigue could actually be an imbalance in specific vitamins, minerals, and/or hormones. All of which can easily be tested for by your family doctor.
Below, I’ll describe each of the lab tests I recommend you have done as well as two different reference ranges you should use to interpret your results.
- Conventional reference ranges
- Function reference ranges
The conventional reference range is what your doctor will use to determine whether (or not) you have a disease/illness. This reference range is not conducive to health. It measures disease. Conventional reference ranges were created using unhealthy controls. Consider diabetes. As more and more people develop diabetes (and pre-diabetes) than ever before, the “normal” blood sugar level continues to increase. This is not reflective of healthy populations. It is reflective of populations with higher numbers of diabetes.
Remember, normal does not equate to healthy.
Functional reference ranges are created using healthy members of the population to determine what the ideal or healthy range should be. Instead of testing people with diabetes/blood sugar imbalances to determine what the average or normal range is, functional ranges track healthy members of a population – those without any blood sugar issues to determine where healthy (not normal) blood sugar levels should be.
I’d encourage you to use the functional range in interpreting all of your lab results. Let’s get going – here are the four lab tests your doctor needs to run if you’re fatigued!
1. Serum iron and ferritin
Serum iron:
Serum iron measures the amount of iron in transit through your blood. If you’ve just eaten a big serving of beef liver, you’re likely to have an increase in serum iron. This is why testing only serum iron is not sufficient to determine whether (or not) you have sufficient iron stores.
Serum iron should always be tested with ferritin and a CBC (complete blood count).
Conventional reference range: 40–155 µg/dL
Functional reference range: 40–135 µg/dL
Both high and low levels of iron can be a cause of fatigue. If either value is out of range, encourage your doctor to explore further testing.
Ferritin:
Ferritin is the storage protein for iron. Ferritin stores and slowly releases iron in a non-toxic and controlled way, which helps protect against iron deficiency and iron overload. Ferritin can also be utilized by your body to protect it against oxidative stress and inflammation. A wide variety of acute and chronic inflammatory conditions (like chronic fatigue syndrome) involve the production of cells/proteins that increase ferritin levels.
If you’re not dealing with CFS, serum ferritin is an excellent indirect marker of the total amount of iron stored in your body. This is no longer true in chronic fatigue syndrome, as ferritin plays the dual roles of iron storage protein and acute-phase reactant. If you have CFS, you cannot rely solely on ferritin as a marker for iron levels. It is likely to be elevated to help your body better manage inflammation.
Normal serum ferritin may either indicate a healthy iron level or a state of simultaneous iron deficiency and inflammation. High ferritin may indicate iron overload, inflammation, or both. Many conditions involving blood loss are also inflammatory, in which case ferritin may be low, normal, or high. As a general rule, inflammation elevates ferritin concentration approximately threefold.
In summary, inflammatory conditions like chronic fatigue syndrome will alter your ferritin levels. Monitor them regularly. See if high or low ferritin levels correlate with the degree of fatigue you experience.
Conventional reference ranges:
Male: 30–400 ng/mL
Female: 15–150 ng/mL
Functional reference ranges:
Male: 30–200 ng/mL
Female: 30–100 ng/mL
2. Vitamin B12
Vitamin B12 (cobalamin) is one of the water-soluble B vitamins. You may know it as the vitamin vegans and seniors are commonly lacking. Or, as the vitamin that’s supposed to give you energy.
Vitamin B12 is particularly important for the formation of health and good-functioning red blood cells. If you’re lacking red blood cells, your tissues will not be supplied with enough oxygen. This creates fatigue. Especially of the muscular variety.
Vitamin b12 also plays an important role in nervous system development and neurological function. The numbness/tingling you experience in your hands/feet, that could be caused by a B12 deficiency.
All of us humans are unable to make our own B12. It has to come from an outside source. Namely, your diet (or through supplementation). Contrary to what your vegan friends may tell you, vitamin B12 is not easily obtained through fruits/vegetables. Meats (especially organ meats) contain the only easily absorbable forms of B12.
Low levels of vitamin B12 is called hypocobalaminemia. It’s brought about through inadequate consumption of vitamin B12 in the diet (vegan/vegetarian), gastric diseases (GERD), and malabsorption (low stomach acid) are the main causes of low vitamin B12.
Elevated vitamin B12 levels (hypercobalaminemia) are almost always caused by excessive intake of vitamin B12 through supplementation. But you would be wise to know that various solid and blood cancers can also cause abnormally high levels of circulating vitamin B12. So, if you have really high B12 levels and you’re not supplementing, have your doctor do some further investigation!
Conventional reference range: 211–946 pg/mL
Functional reference range: 450–2000 pg/mL
3. Vitamin D
25-hydroxyvitamin D, also known as calcidiol or calcifediol, is one of the two main biologically active forms of vitamin D. Adequate vitamin D is required for normal function of muscle tissue, nervous tissue, and cells of your immune system.
Low 25-hydroxyvitamin D arises from decreased consumption of vitamin D, inadequate synthesis of precursors in the skin, decreased synthesis in the liver, increased breakdown, or loss from the kidneys.
The most common cause of elevated serum 25-hydroxyvitamin D levels is an excess intake of vitamin D. Excess sun exposure does not lead to increased 25-hydroxyvitamin D levels, since sustained heating of the skin will photodegrade the vitamin and its precursor.
As my practice is located in Canada, a lot of my patient population take mega-doses of vitamin D for long periods of time. All too often, this can lead to toxic levels of vitamin D. Vitamin D is a fat-soluble vitamin. Meaning that you cannot pee out the excess like you can with B vitamins.
To further complicated matters, the symptoms of high/toxic levels of vitamin D are so similar to the symptoms associated with low levels of vitamin D. More info on that here. The key takeaway here is to test.
Measure your vitamin D levels in the fall to make sure you have enough vitamin D as you go into the winter months. Measure again in the spring to ensure your vitamin D stores haven’t been depleted during the winter months. Testing vitamin D levels 2x/year is the best way to ensure your supplementation is aligned with your body’s need.
Laboratory reference range: 30–100 ng/mL
Functional reference range: 35–60 ng/mL
4. Full thyroid panel
Contrary to what your doctor may tell you, testing TSH alone is not enough to determine whether or not your thyroid is functioning properly. Below, I outline all the tests necessary for a detailed thyroid panel. If you want a more thorough explanation of how your thyroid is connected to chronic fatigue, click here.
TSH:
TSH stands for thyroid-stimulating hormone, although it is sometimes called thyrotropin or thyrotropic hormone. TSH stimulates your thyroid gland to produce thyroid hormone. TSH is what is known as an inverse marker. Meaning it’s elevated when you have hypothyroidism (low thyroid) and suppressed when you have hyperthyroidism (elevated thyroid).
High levels of circulating TSH are usually caused by primary hypothyroidism or subclinical hypothyroidism. Abnormally low levels of circulating TSH are usually caused by primary hyperthyroidism or subclinical hyperthyroidism.
Laboratory reference range: 0.45–4.5 µIU/mL
Functional reference range: 0.5–2.0 µIU/mL
Free T3:
Triiodothyronine (T3) is the most biologically active thyroid hormone in your body. The fatigue you experience from an under-functioning thyroid is likely due to the low circulating levels of T3.
Decreased free T3 levels in the serum usually indicate hypothyroidism. Elevated free T3 levels usually indicate hyperthyroidism.
Laboratory reference range: 2.0–4.4 pg/mL
Functional reference range: 2.5–4.0 pg/mL
T4:
T4 is the molecular precursor of T3 (triiodothyronine). T4 gets converted to T3 in your gut. T3 is significantly more potent than T4 at thyroid hormone-responsive receptors. Meaning that low T3 will have a much more profound impact on your energy than low T4.
Laboratory reference range: 0.82–1.77 ng/dL
Functional reference range: 1.0–1.5 ng/dL
Thyroid peroxidase antibodies:
TPO, as it’s commonly seen on lab reports, stands for thyroid peroxidase antibodies. Thyroid peroxidase is an enzyme that is integral to thyroid hormone synthesis in the thyroid gland. Unfortunately, this enzyme can also become an antigen in autoimmune thyroid disease (Hashimoto’s).
It is abnormal to find thyroid peroxidase antibodies in your blood. Often, these antibodies can go out of range before T3, T4, and TSH values. This results in a condition known as euthyroid sick syndrome. Euthyroid sick syndrome is often a hidden cause of fatigue.
If you are creating thyroid peroxidase antibodies, your immune system is directing an attack on your thyroid gland. This destroys thyroid follicles. Eventually, this may lead to an inflammation of your thyroid gland (thyroiditis) and often will result in hypothyroidism.
It’s completely normal to have a small number of thyroid peroxidase antibodies in your blood. Just ensure they’re kept below 34IU/mL
Laboratory reference range: 0–34 IU/mL
Thyroglobulin antibodies:
Much like thyroid peroxidase antibodies, it is abnormal to have thyroglobulin (Tg) antibodies in your blood. Tg antibodies in the blood often indicate chronic autoimmune thyroiditis (Hashimoto’s disease).
The mechanism by which the immune system produces autoantibodies against Tg is unknown, but leading hypotheses believe that an initial infection initiates the autoimmune process. A viral illness is considered the most common cause, but an injury to the thyroid gland, pregnancy, and excessive iodine intake may also trigger this process.
Tg and TPO antibodies are present in roughly 90 percent of people with Hashimoto’s thyroiditis and 50 to 80 percent of people with Graves’ disease. Tg antibodies, like TPO antibodies, may be present in subclinical hypothyroidism, indicating an elevated risk of progressing to overt hypothyroidism
Laboratory reference range: 0–0.9 IU/mL
Ok, there you have it, 4 tests you need to get your family doctor to run before any additional digging is done into the cause of your fatigue.
Now, I want to hear from you!
What lab tests helped you overcome fatigue?
What if reverse t3 is high. You didn’t mention testing RT3.
My naturopath tested for this and my gp didn’t know what it was.
Hey, Kim!
Great question!
Reverse T3 does not stimulate nuclear thyroid hormone receptors and, as such, is considered an inactive thyroid hormone. Reverse T3 levels are most useful in a clinical setting as a means of distinguishing between nonthyroidal illness and primary thyroid disease.
Assuming your other thyroid markers are in range (T3, T4, TSH), elevated reverse T3 can be caused by protein-calorie malnutrition, carbohydrate deprivation, chronic renal failure, cirrhosis, and uncontrolled diabetes. Though it’s most commonly elevated when there’s a lack of oxygen reaching your tissues (ischemia and/or hypoxia).
M
What’s with the rudeness toward vegans on this page? Please educate yourself on where B12 comes from. Animals are supplemented with B12. I would advise people to look elsewhere for information.
Regardless of whether animals are supplemented with B12 or not, omnivores are far less likely to develop vitamin B12 deficiency. 92% of vegans and 77% of vegetarians were found to have a vitamin B12 deficiency. Compare that to only 11% of omnivores. (source).
If you’re going plant-based, make sure you’re supplementing B12!
M