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Making Sense of Your Blood Test

Nurse swabs a woman's arm in preparation for blood test

It is common for primary care physicians to provide their patients with the results of their blood tests. We look at the results and hope to see normal levels across the board. But how many people actually take the time to understand what is actually being tested? If this sounds like you, let’s take a minute to walk through the meaning behind the various values.

A blood test is typically composed of three main tests: a complete blood count, a metabolic panel and a lipid panel, so let’s break them down.

Complete Blood Count (CBC)

The CBC concentrates on the three types of blood cells: white blood cells (WBCs), red blood cells (RBCs), and platelets. By measuring the volume of blood cells, the CBC allows a doctor to evaluate an individual’s overall health, as well as check for underlying conditions such as leukemia and anemia.

White Blood Cell Count (WBC)

White blood cells, also known as leukocytes, are a major component of the body’s immune system. A high white blood cell count can indicate the presence of infection, while a low count can point towards various conditions, including HIV/AIDS and lupus.

Some blood tests will include something called a “Differential White Blood Cell Count.” The lab tests the five main components of white blood cells and their proportion to each other. If the components are out of balance, this could indicate an infection, as well as a variety of medical conditions. Healthy proportions for each are:

  • Neutrophils: 40 to 60 percent of the total
  • Lymphocytes: 20 to 40 percent
  • Monocytes: 2 to 8 percent
  • Eosinophils: 1 to 4 percent
  • Basophils: 0.5 to 1 percent

Red Blood Cell (RBC) Count

Red blood cells carry oxygen to tissues throughout the body, making them important to its healthy functioning. A red blood cell count estimates the volume of RBCs within an individual.

Hematocrit (Hct)

This tests what proportion of the blood is made up of RBCs. It is useful in diagnosing anemia, among other medical conditions.

Hemoglobin (Hgb)

Hemoglobin is a protein contained within RBCs that sends oxygen from the lungs to the body’s tissues. The hemoglobin test is useful in diagnosing anemia.

Mean Corpuscular Volume (MCV)

This is the average volume of RBCs or the space each red blood cell fills. Results outside of the normal range can be a sign of anemia or chronic fatigue syndrome, among other medical conditions.

Mean Corpuscular Hemoglobin (MCH)

Tests the average amount of hemoglobin present in each red blood cell. High levels are a possible indicator of anemia and low levels can be a sign of malnutrition.

Red Cell Distribution Width (RDW or RCDW)

Tests the distribution of RBCs, not their actual size. Levels outside of the normal range can indicate conditions such as anemia, malnutrition, and liver disease.

Platelet Count

Platelets are small cells that help the blood to clot. This test measures the number of platelets present in the blood. If testing highlights a high count, this can indicate anemia, cancer, or infection, while a low count can prevent wounds from healing and result in severe bleeding.

Mean Platelet Volume (MPV)

Tests the volume of platelets in the blood. A low platelet volume can cause irregularities with bleeding, while a high platelet volume can increase an individual’s risk of heart attack or stroke.

Comprehensive Metabolic Panel (CMP)

The comprehensive metabolic panel test, also known as a chemistry panel, measures the body’s glucose levels, fluid and electrolyte balance, as well as liver and kidney function. It consists of a number of sub-tests:

Alanine Aminotransferase (ALT)

Alanine aminotransferase (ALT) is an enzyme mostly produced by liver cells. High levels can be an indication of liver damage.


Albumin is a protein produced by the liver. Its volume within the organ can be measured via this test. Abnormal levels can be caused by liver or kidney problems.

Total Protein

The lab tests the ratio of two types of proteins: albumin and globulin. Low protein levels can indicate various conditions, including liver and kidney disorders and malnutrition, while high levels can be a sign of inflammation, infection, or bone marrow disorder.

Alkaline Phosphatase

Alkaline phosphatase is an enzyme typically produced in liver and bone cells. Results outside of the normal levels can signal liver damage and bone problems such as rickets or bone tumors.

Aspartate Aminotransferase

Aspartate aminotransferase is an enzyme usually found in RBCs and muscle tissue, as well as the heart, pancreas, liver, and kidneys. This test measures the levels of this enzyme in the body, with results above the healthy range indicating a variety of conditions, including some types of cancer, as well as liver, heart or kidney damage.


Tests for kidney and liver dysfunction which is useful in diagnosing conditions such as neonatal jaundice, anemia, and liver diseases.

Blood Urea Nitrogen (BUN)

This measures the volume of nitrogen in the blood. High levels can be caused by kidney damage or disease, while low levels may be a sign of malnutrition or severe liver damage.


This measures the levels of calcium in the blood. If testing indicates low levels, this can indicate cancer, hyperparathyroidism, tuberculosis, and other conditions, while high levels can indicate conditions including malnutrition, rickets, and hypoparathyroidism.


This test measures the body’s chloride levels. An increased level of chloride can indicate dehydration as well as kidney disorders and adrenal gland dysfunction.


Creatinine is a chemical waste molecule that is important for creating muscle energy. Increased levels of creatinine can be a sign of kidney dysfunction.

Fasting Blood Sugar

Blood sugar levels are easily affected by recent food or drink intake. The fasting blood sugar test is therefore done after a minimum of six hours of fasting. Abnormal results can indicate diabetes, among other medical conditions.


Tests the amount of phosphorus in the blood. Elevated levels can indicate problems with the kidneys and parathyroid glands, and they may be a sign of malnutrition or alcohol abuse.


Potassium aids the communication between nerves and muscles regulates the heart and maintains muscle function.


Sodium is a mineral that aids nerve impulses and muscle contractions, as well as balancing water levels. Irregularities are a possible indication of dehydration, adrenal gland disorders, corticosteroids, and kidney or liver disorders.

Lipid Panel

The lipid panel consists of various tests used to measure the different types of triglycerides (fats) and cholesterol in the blood.

Total Cholesterol

This test measures the overall levels of LDL (bad) and HDL (good) cholesterol in the blood.


Tests for triglycerides, a fat found in the blood. Irregularities are a possible risk factor for heart disease and other medical conditions.

HDL Cholesterol

HDL cholesterol, also known as high-density lipoprotein (or good cholesterol), is useful in protecting against heart disease. Low levels can increase the risk of heart problems.

LDL Cholesterol

LDL cholesterol, also known as low-density lipoprotein (or bad cholesterol), is linked to heart disease and clogged arteries.

Total Cholesterol to HDL Ratio

Calculating this ratio can help determine an individual’s risk of developing heart disease. It is worked out by dividing HDL cholesterol into total cholesterol. High levels are a possible indicator of heart problems.

It is common for certain blood test values to temporarily fall out of the normal range. While this can signal the presence of a health condition that requires attention, more often than not the cause is benign and no cause for concern. Now if you see such a value on your blood test, you’ll what that value measures. Stay healthy.

Do you have a case? Feel free to contact our team at Rourke & Blumenthal for a free consultation. We can be reached by phone at (614) 321-3212 or online.

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