Understanding Lab Test Result Ranges and Why “Normal” Does Not Always Mean Healthy

by Dr. Susan Tanner, MD

Many patients with chronic fatigue and mold-illness symptoms have been told by their primary physician and other doctors that all their lab work is “normal”; therefore, there is nothing wrong with them.  These are devastating words for one who has been suffering and can create an atmosphere of self-doubt and confusion.  Patients then distrust their bodies and begin asking themselves, “How can I feel so terrible, yet my lab work is ok? Is it all in my head?” It is my hope to shed some light on this topic in today’s article.

Basic Lab Work

Basic lab work, as is done at a routine physical, is helpful–to a point.  If there are distinct abnormalities that indicate pathology or infection, then these will usually show up readily and can be addressed.  Applying what we know about biology and physiology to chemical bloodwork, however, can yield much more information about the processes of the body and can be helpful for identifying the root cause of a symptom or for when the disease process is beginning BEFORE the patient is actually quite sick. Normal ranges as given by the lab from which to evaluate a patient’s results are actually averages of what was found in certain pockets of the population and do not always correlate with ideal levels of health and functionality. These normal distribution ranges are usually based on a Bell curve which includes both people who are well and people who are sick. Such ranges, therefore, make it difficult to determine where a healthy person’s results should fall.

Examples of “Normal” Lab Results That are NOT Optimal for Safeguarding Health

(Note: The following examples just scratch the surface. It would be beyond the scope of this article to try to address all areas where conventional test ranges fail to indicate health issues. These are intended to give you a good starting point for further reading and investigation.)

Red Blood Cells

Mean corpuscular volume level or MCV level on a blood count describes the size of the red blood cells.  The higher the number, the larger the blood cell. Large red blood cells are often associated with Vitamin B12 deficiency.  The range of “normal” for MCV on blood counts is 79-97.  From delving more deeply into biochemistry, it is noted that once a patient’s MCV level starts going above 92, then it is likely there is a need for more B12 in the cells. B12 not only helps with energy but is also a key player in a biochemical function called “methylation”.   Methylation is a huge component for detoxification of the liver, for brain health, and to provide immune protection to the body from oxidative stress. Thus, ideally, you would want to address a high MCV level BEFORE lab results are officially “abnormal”.

Vitamin B12

Normal (per the lab) blood levels of Vitamin B12 range from 300-1000.  But it is reported in numerous studies that neuropathy (numbness and tingling of the feet/legs) can occur with levels below 400.  And measuring B12 in the blood can be affected by recent ingestion of B12 or foods high in it, and may contribute to not getting an adequate picture of the truth of deficiency.  A far more reliable blood test for B12 levels is methylmalonic acid, which is elevated in cases of true B12 deficiency. However, rarely is this test done in routine settings. Low levels of B12 or high levels of methylmalonic acid then raise the question of the possibility of intestinal malabsorption which then requires further investigation.

Liver Function

Liver functionality is assessed through levels of certain enzymes, ALT, AST, alkaline phosphatase, and GGT.  GGT (gamma-glutamyl transpeptidase) has been eliminated from the routine chemistry panels for some unknown reason, as its elevation and diminution are far more sensitive than ALT and AST in assessing changes to liver status. In integrative medicine, GGT is a very valuable tool for looking at glutathione status. Glutathione is an extremely important antioxidant; we have discussed it in prior articles in more depth.  The reference interval per the lab for GGT is 0-60.  Pretty wide range, right?  What we know when looking at function is that the ideal range is actually is between 15-30   Too low, and there is not enough glutathione in circulation.  Too high and not enough glutathione is getting into the cells. Inadequate levels of glutathione in the body may point to environmental exposure (mold, chemicals) or chronic illness, such as a viral infection or Lyme disease. Certain prescription medications and diet can also affect GGT levels, which should be considered. Obviously, in order for the best health possible, a doctor would want to help support a patient with suboptimal levels with things like glutathione supplementation or added liver support and liver-protective nutrients.

Vitamin D3

Vitamin D3 levels are reported as normal between 30-100.  Again, for ideal function, levels need to be at least between 60-80.  As Vitamin D is an integral part of bone, immune, and brain health, optimizing these levels is extremely important.


In certain mineral levels, such as zinc and magnesium, some labs are reported as serum levels.  Again, examining functionality shows that one must look at what is inside the red blood cell level to truly get an accurate picture of how deficient (or not) one might be in these essential minerals; they are called RBC levels.   Magnesium is one of the most deficient minerals in all of us! Supplementation, sometimes long-term, is needed for many patients in this arena.


The thyroid is often screened simply by looking at a TSH level, (thyroid-stimulating hormone) which is produced by the pituitary to tell the thyroid to work.  Normal levels per lab, are 0.45-4.50.  The higher the TSH, the lower the thyroid.  Once again, in functionality ideals, TSH should be below 2.0. Looking only at TSH for thyroid function, however, only shows part of the picture.  Free levels of hormones, T3 and T4 must be done to not only see how much hormone is being produced by the gland but also to show how this is converting into the active form of thyroid, which is T3.  Many times I have cases of normal TSH, but very low levels of Free T3.  Correcting this may require supplementation of iodine, zinc, and tyrosine but also may require specific thyroid medications to restore normalcy of function.  I also would want to look into contributing factors that may be affecting thyroid health, like mold or autoimmune diseases. Sometimes, I even like to try patients on homeopathic pituitary support products, like CellTropin, to see if their bodies just need a nudge to start functioning properly, or need something more, like Rx thyroid support.

Functional Testing for a Better, More Comprehensive Health Picture

There are other clues that point to imbalances or problems based on the initial or usual bloodwork.  From there, however, it is up to the practitioner to determine if additional functional testing is needed. As I noted earlier, it is beyond the scope of this article to mention them all or to explain exactly what each test does, but one of my “go tos” when I really need to see the best picture of the internal biochemistry of the patient is the Organic Acids Test.  Not only does it show the byproducts of yeast and other undesirable bacteria in the gut, but it also shows the likelihood that mycotoxins, whether inhaled from the environment or in the patient’s diet, are creating that impact.  It also reflects the health of the mitochondria which are the powerhouses of the cells and thus the entire body.  If the mitochondrial function is impaired, then there will be fatigue as well as an increased risk of disease. Some vitamin deficiencies show up as well in organic acids testing. The greatest thing is that this test is done from first-morning urine, which is also a plus because there are no needles or blood required!

Comprehensive Digestive Stool Analysis is another very helpful test to determine if there are specific bacteria or parasites in the intestinal tract. It also reveals products of digestion that examine if pancreatic function is sufficient and if there is inflammation suggestive of inflammatory bowel diseases such as ulcerative colitis or Crohn’s disease.  Because most of the labs conducting this test use DNA probes to evaluate for bacteria and parasites, it is far more sensitive than the usual stool cultures done in routine lab settings.

There are many other tests available that involve in-depth evaluation of adrenal and hormonal function that may be conducted on saliva or urine. These tests give a clearer picture of hormone levels than a one-time blood test.

Mycotoxin-Specific Lab Tests

I would be remiss if I did not mention specific labs for mycotoxins.  There is no blood test that is easily done to look for specific mold/mycotoxins in the body.  We get suggestions of them by looking at inflammatory markers such as TGFbeta1 and IgG mold levels, which may indicate exposure, but urine mycotoxin testing shows levels of the chemicals produced by molds and is about as accurate as we can get for this. RealTime Laboratories and Great Plains Laboratory are the two that I am most familiar with.

When You Are Looking for Answers

My point in writing this is to let you, the walking wounded, the sufferers of less than optimal health, know that just because your routine lab work may look ok, it does NOT mean that you are ok.  Find a practitioner who is willing to dig deeper with you to find what is really happening under the surface! A practitioner trained in functional medicine can actually listen to a patient and decide what labs will lead to proper discovery. Then, that practitioner can skillfully interpret the results to best help the patient. The interpretation of the lab results is sometimes more important than the results themselves, so do not discount this step! A good practitioner knows what to look for and then digs deeper for the story that those lab results are telling.

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