How to Interpret Your Blood Tests: Part I

Analyzing blood chemistry can be a very helpful tool in determining what a patient needs to improve their health, and of course why a patient is experiencing certain signs and symptoms. A patient will often bring in their blood work to me and tell me that the doctor who ordered the tests said everything was normal. Whether or not I agree that their tests are normal, these patients never understand what all the tests mean and how to interpret them. Of course, that’s the doctor’s job, but there are many patients out there who do want to understand and wish their doctor would explain the meaning behind them. Because of this, I decided to write a series of articles explaining what these blood markers mean and how they are relevant.

There are hundreds of tests that can be ordered via blood, but the basics are a “Complete Blood Count” (CBC) and (comprehensive) “Metabolic Panel”. Very often a lipid (or cholesterol) panel is ordered as well. In this first article I’ll go over how to read and understand the red blood cell markers that are included in a CBC.

A CBC reports three different cell types in the blood: 1) red blood cells, 2) white blood cells, and 3) platelets.

Let’s begin. Red blood cells are responsible for delivering oxygen from the lungs to the body tissues, and to take up carbon dioxide from the tissues and bring it to the lungs. The CBC includes information on seven different aspects of red blood cells (RBC). I’ll go over each individually.

1) “Red Blood Cells” (RBC) – This value refers to the actual number of RBC in a given sample size. When this is decreased, it means there is an insufficient number of RBC available to supply adequate amounts of oxygen to the tissues. This would be considered “anemia”. There are many types of anemia that may be present and describing each is beyond the scope of this article. Also, keep in mind that someone can be anemic and have a normal number of RBC. Red blood cells can be low in number because of iron-deficient diets, blood loss [normal (as in menstruation) or traumatic or pathological], malabsorption, pregnancy, or during growth spurts. An increased number of RBC is more rare to see, and that would typically be a result of dehydration. This is because dehydration would increase the concentration (or total number) of RBC in sample of blood that has a low amount of water in it. Additionally, RBC may be increased due to a bone marrow disorder (where RBC are made), low atmospheric oxygen (e.g.: high altitude areas), poor lung function, or a malignancy.

2) “Hemoglobin” (Hgb) – Hemoglobin is the oxygen and carbon dioxide-carrying portion of the RBC and is responsible for giving blood it’s red color. As the name suggests it is composed of heme, which contains iron, in addition to the protein “globin”. The amount of Hgb in the RBC is directly related to the amount of oxygen the RBC can carry. When Hgb is low, it usually indicates (iron-deficiency) anemia. And as with RBC, if it is high, it would usually indicate dehydration or the other conditions mentioned above.

3) “Hematocrit” (HCT) – The HCT is the percentage of RBC in the entire blood sample, and therefore is a measurement of RBC production. This would be low in most types of anemia and high in a dehydrated person or the other conditions mentioned above regarding RBC and Hgb.

4) “Mean Corpuscular Volume” (MCV) – The MCV is a measure of the average size of the RBC. This marker is key for identifying anemia and differentiating between the many types of anemia. Red blood cells start out large and shrink in size as they mature to become fully functional. If the MCV is high (meaning the RBC are larger than normal), it typically indicates a deficiency of folic acid and/or vitamin B12 because these are the two nutrients required for RBC to mature (and shrink in size). When the MCV is low (meaning the cells are smaller than normal), it usually indicates iron deficiency as there is actually less volume to the cell because there is less mass with insufficient amounts of iron. There are other reasons this value can change due to other types of anemia, which is beyond the scope here.

5) “Mean Corpuscular Hemoglobin” (MCH) – The MCH is a measure of the average amount of Hgb in each RBC. This value helps with determining the severity of anemia. MCH is typically low in iron-deficiency anemia and might be high in B-12 and/or folate-deficiency (megaloblastic – meaning large cells). It would be high in megaloblastic anemia because the cell is larger and therefore has the ability to contain more Hgb.

6) “Mean Corpuscular Hemoglobin Concentration” (MCHC) – The MCHC is (just what it sounds like) a measure of the concentration of Hgb in a given amount of RBC, and will most likely be low or high for the same reasons as MCH. This value is especially useful in monitoring therapy for anemia.

7) “Red Blood Cell Distribution Width” (RDW) – The RDW is a value that measures the average size of all the RBC present in the sample. A low RDW would indicate that most RBC are too small as in the case of iron-deficiency. And a high RDW would point to there being too many large RBC as in B12 and/or folic acid-deficiency anemia. It would certainly be too high or low because of other types and causes of anemia.

Keep in mind that this article does not cover all types and causes of anemia. It is intended as a guide to understanding the terminology used on blood tests and some of the most common reasons for abnormally high or low values. Additionally, the reference ranges for normal values can, and often do, vary from lab to lab. This is because the reference ranges are typically determined from averages that the labs have constructed based on the many samples that they have tested. As a result, I usually find these ranges too wide to assess the risk for disease before it develops. When the blood values are outside of the lab’s reference ranges, a disease (or disease process) is usually already in place. I prefer to assess blood work using more narrow, “functional” ranges that can detect disease before it is “full-blown”, and to prevent disease.

Clinical pearl: when a patient is doing “everything right” for themselves (i.e.: diet, exercise, proper supplements, etc.) but they do not respond to those treatments; usually a sub-clinical anemia can be found. Without proper oxygen supply to the body’s tissues, there is little to no chance the body will be able to heal or function better.

Dr. Robert D’Aquila – NYC Chiropractor – Applied Kinesiology