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Interpreting your lab results

Blood tests are used for several reasons including to diagnose a condition, to rule out certain diseases, to monitor an already diagnosed condition, to monitor a treatment plan, or to check your overall general health. With all these reasons in mind, it is likely at some point in life you will require a blood test. 

However, the results can be confusing, even when a doctor is explaining them to you. Test results are not always negative or positive, they may be borderline, inconclusive, numerical, reactive, non-reactive, and even your gender may affect the result. An abnormal result does not always mean you are unwell, just as a normal result does not always mean you are healthy. Blood test results can be perplexing, to say the least. 

For this reason, this simple guide will give you a basic understanding of some of the more common tests. Having a basic understanding of blood test results will allow you to feel more confident and in control of understanding your medical care. 

What do my results mean?
With hundreds of types of laboratory tests, it is impossible to cover them all. Therefore this section will focus on the basics and most common blood tests. 

Common abbreviations

Abbreviation

Meaning

cmm

Cells per cubic milliliter

fL (femtoliter)

Fraction of one-millionth of a liter

g/dL

Grams per deciliter

IU/L

International units per liter

mEq/L

Milliequivalent per liter

mg/dL

Milligrams per deciliter

mL

Milliliter

mmol/L

Millimoles per liter

ng/mL

Nanograms per milliliter

pg

One-trillionth of a gram

mcL

Microliter



What is a reference range?

When looking at your lab results you may see something called a reference range, which is also known as normal values. This range of normal values is determined by examining the normal test results of a large group of healthy people. It shows the range within which most typical people's test results will sit. 

It is important to remember that not everyone is 'typical'. Your results may fall within the normal range but you could still be experiencing symptoms. Or, you may be completely healthy and your results fall outside of the reference range. In both of these scenarios, you will need further investigations. 

False positives and negatives.
Although rare, it is possible to test positive for a condition you don't have or test negative for a condition you do have. There are lots of reasons that this may happen including the test not being carried out correctly, being carried out at the wrong time, or problems with the equipment. Although it is not common, it is important to understand that it can happen.

Components of common blood test results and how to interpret them

CBC (Complete Blood Count)
A CBC measures the volume of blood cells that make up your blood. It identifies if the body is making the right number of each type of cell, and it can highlight issues such as infection, bleeding, certain diseases, or clotting problems. There are several different sub-tests within a CBC and here are a few of the most important ones:

Test name

Overview

Reference range
(normal range)

White blood cell count (WBC)

White blood cells, also known as leukocytes, help you to fight infection. A high white cell count may indicate that there is an infection present or possibly a disease like leukemia. A low white blood cell count can indicate conditions such as autoimmune diseases.

WBC per microliter of blood (mcL):

  • 9,000 to 30,000 for newborns.
  • 6,200 to 17,000 for children under two years old.
  • 5,000 to 10,000 for children above age two, up to adults.

Differential white blood cell count 

White blood cells are made up of five different components. This test measures the volume, shape, and size of these different components. If they are out of balance, it identifies that there may be an infection or medical condition present.

Neutrophils
2500-8000 per mm3 
(55-70%)
Lymphocytes
1000-4000 per mm3 
(20-40%)
Monocytes
100-700 per mm3 
(2-8%)
Eosinophils
50-500 per mm3
(1-4%)
Basophils
25-100 per mm3 
(0.5-1%)

Red blood cell count (RBC)

Red blood cells, also known as erythrocytes, carry oxygen through the body. This test checks the volume of red blood cells in the body. If the results are above or below the reference range, it can indicate that a medical condition is present. However, further tests would be needed to determine the problem.

Men:
4.7 - 6.1 million mcL.

Women (not pregnant):
4.2 - 5.4 million mcL.

Children:
4.0 - 5.5 million mcL.

Hematocrit test (Hct)

Determines how much of the total blood volume in the body consists of red blood cells and is useful for diagnosing anemia.

Men 42-52%.
Women (not pregnant) 37-47%.
Children 32-44%.

Hemoglobin test (Hgb)

Hemoglobin is what delivers oxygen from the lungs to the body and makes your blood red. Low hemoglobin levels can indicate anemia.

Men 14-18 g/dL.
Women (not pregnant) 12-16 g/dL.
Children 9.5-15.5 g/dL

Platelet count

Platelets are involved in clotting and too many, or too few platelets, can affect how your blood clots.

150,000 to 400,000 mL


Comprehensive Metabolic Panel (also known as chemistry panel)

A comprehensive metabolic panel measures glucose levels, fluid and electrolyte balance, liver function, and kidney function. There are several different sub-tests within this panel and here are a few of the most important ones:

Test name

Overview

Reference range
(normal range)

Total protein test

Also known as albumin/globulin ratio or A/G ratio. Albumin and globulin are the two types of protein found in your blood and raised levels can indicate inflammation, infection, or a bone marrow disorder. Low levels can indicate malnutrition, a kidney problem, or a liver problem.

A/G ratio is normally slightly higher than 1.

Glucose test

This measures the amount of Glucose in your blood. This testing is typically done for those with Diabetes.

Normal: 140 mg/dL or lower
Prediabetes: 140-199 mg/dL
High: 200 mg/dL and higher

ALT Test

Alanine Aminotransferase Test (ALT) is used to diagnose Liver disorders. ALT is a liver enzyme that is released into the bloodstream when liver cells have been damaged.

Men:
29-33 IU/L

Women:
19-25 IU/L

AST

Aspartate Aminotransferase (AST), also known as SGOT, is used to measure the amount of this enzyme in the blood.

5-40 IU/L

Alkaline phosphatase test

This is an enzyme produced in both liver and bone cells. Therefore, results outside of the reference range can indicate bone or liver problems.

44 to 147 IU/L

Calcium test

Measures the level of calcium in the blood. Low levels may indicate cancer, tuberculosis, and other problems. High levels may be due to problems like rickets or malnutrition.

8.5 to 10.5 mg/dL (lower in the elderly)

Creatinine test

Creatinine is a waste product produced by the kidneys, therefore levels outside of the reference range may indicate a kidney problem.

Men:
60-110 µmol/L
(0.7-1.2 mg/dL)

Women:
45 to 90 µmol/L
(0.5 to 1.0 mg/dL) 

Phosphorus test

Phosphorus is related to calcium and bone health. High levels can indicate a problem with your kidneys or the parathyroid gland.

3.4-4.5 mg/dL
(1.12-1.45 mmol/L)

Sodium test

Sodium is a mineral that helps your body balance water levels and helps with nerve impulses and muscle contractions. Levels outside of the reference range can be for several reasons such as dehydration, high salt intake, levels of medications, kidney problems, or liver problems.

135 to 145 mEq/L

 

Lipid Panel
This measures the different types of triglycerides and cholesterol (fats) in the blood. Common sub-tests within a lipid panel include:

Test name

Overview

Reference range
(normal range)

Total Cholesterol Test

Measures the total level of cholesterol in your blood (good- HDL and bad LDL).

Healthy
Below 200 mg/dL
(below 5.18 mmol/L)

Borderline high:
200 to 239 mg/dL
(5.2 to 6.2 mmol/L)

High:
Above 240 mg/dL
(above 6.2 mmol/L)

Triglycerides test

Triglycerides are a type of fat found in the blood that link to both heart disease and diabetes.

Normal: less than 150 mg/dL
Borderline-High: 150-199 mg/dL
High: 200-499 mg/dL
Very High: 500 mg/dL

HDL cholesterol test

Good cholesterol

Optimal: Above 60 mg/dL

Good: 50 to 60 mg/dL

Poor: Below 40 mg/dL for men and below 50 mg/dL for women.

LDL cholesterol test

Bad cholesterol

Optimal: Less than 100 mg/dL
Near optimal: 100-129 mg/dL
Borderline high: 130-159 mg/dL
High: 160-189 mg/dL

 

These are just some of the more common lab tests that you may encounter. Understanding your test results is essential in being proactive with your health. It can give you a better understanding when your doctor is talking through your results. However, if you are ever confused about your test results, or do not fully understand them, then reach out to your doctor for advice. It is ok to ask questions. Private MD Labs is here to provide confidential laboratory testing to individuals who take charge of their own health. You can order your lab tests online through our website or call us at (877) 283-7882 for further information.

 

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