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What can be learned from a blood sample?

July 3, 2019

Diseases can infect any part of the human body.  They can develop and spread for years without any symptoms, or at least only mild symptoms.  Trying to monitor all parts of your body over years and years would be time-consuming and very expensive.  However, there is one system in the body that connects it all, that often cannot help but spill the beans about bad things going on, in one way or another. 

Your blood constantly moves throughout your entire body.  On the one hand, it gives diseases, viruses, infections, etc., an opportunity to spread to new areas.  That is not good.  On the other hand, it is very easy to look at blood and determine if something is not as it should be.  That is a good thing.  It also provides the perfect network to inject medicine into the body and have it spread throughout. 

Using a simple blood sample, hospitals can look for cancer and tumor markers, check liver and kidney function, diagnose autoimmune diseases and infectious diseases, identify infections, anemia, leukemia, and more.  Testing blood samples, like all medicine, is not a perfect science; in some cases, imaging in radiology departments can provide a more precise view of what is going on.  However, outside of certain screenings, radiology is not the recommended first-stop in disease prevention. 

The great thing about blood samples is they can be easily and quickly tested for abnormalities.  The Chemistry profile, for example, gives a broad overview of many levels detectable in the blood.  When a certain level is unusual, it alerts healthcare providers that something might be wrong, and more testing needs to be done.  Medical knowledge is advanced enough to know where to look next based on the tests. 

Naturally, there is variability in expected test results.  People come in all different forms, and everything from size and weight to age and gender can affect blood test results.  Red Blood Cell count, Hemoglobin, Hematocrit, and Alkaline Phosphatase have different ranges for men, women, and children due to physiological differences, and the rule is not “the smaller you are, the lower your levels should be.”  For example, alkaline phosphatase is found in our bones, and children and teens are expected to have higher levels of it because their bones are still developing.

This is why provider information is requested before any screenings are done; hospitals want to make sure providers can appropriately guide the next steps in the prevention process.  They know the appropriate ranges and what potential diseases should be checked based on blood sample results. 

Variability in results is also why certain tests require 12- or 24-hour fasting.  Fasting helps to alleviate variability between patients that would result from different diets.  Tests such as glucose and triglycerides can vary greatly when it is not preceded by fasting.  Providers would agree that it helps to know if your results are normal or abnormal and not just affected by the fact you had fried chicken or a candy bar the night before the lab work was done.  Other tests are not so easily affected by food and can therefore be done without fasting.

The variability does not stem from a lack of technology or medical knowledge, however.  Most lab testing is now done with automated analyzers.  They are built with many safe guards to ensure reliability, on top of regular servicing and quality control.  Lab techs with college degrees often verify results under the microscope to ensure the machines are running properly.  Any time results are questionable, specimen are referred to more advanced laboratories for more in-depth testing.

In other words, setting aside a few minutes to have one vial of blood drawn is one of the smartest things people can do.  A few simple, quick, accurate tests can determine if there are more concerns to explore and set you on the path to prevention or treatment earlier in the disease process, when it is easier to manage and treat.  Waiting for symptoms is the old way; detecting and preventing is the new.

Perry will be hosting a reduced cost health screening on Thursday, July 18.  Learn more at