The common cold is a viral or bacterial infection that causes your body to respond in various ways. These normal bodily processes can affect the results of certain blood tests. Depending on what your doctor hopes to evaluate, your cell counts can change during a cold. This makes it essential to talk with your doctor or the health practitioner administering the test about your cold to find out if you need to postpone your blood work until after you recover. If you need to book blood work, book an appointment today to have this blood work performed from the comfort of your home. And find out below does a cold affect blood tests.
Why Do I Need a Blood Test?
Doctors can order blood tests for a variety of reasons. These include numerous diagnostic procedures based on your symptoms or family history but also routine work done once a year to check the status of your body’s major functions.
What Can Affect Blood Test’s Results?
Infections are not the only thing that can impact the results of a blood test. Any blood test that requires fasting is affected by your body’s metabolic processes, which is why your doctor will order a period of fasting, usually for 8-12 hours before the test. Despite being banned from eating, not drinking enough can also negatively impact your blood test by causing an imbalance of potassium, leading to inaccurate results if that’s one of the things that is being tested.
In addition to food, caffeine could impact certain tests, as could alcohol, which affects your blood sugar in response to activating liver enzymes. Smoking can increase your blood sugar too, as well as hormones like cortisol and lipids like triglycerides, measured during a lipid panel (also known as a cholesterol test).
Medications that you take, like antibiotics, NSAIDs like acetaminophen, steroids, or antidepressants, can impact certain blood levels. Even physical exercise can affect your body’s hormone and glucose levels for hours afterward, leading to inaccurate results.
Knowing this, it should come as no surprise that a cold, which activates inflammatory processes throughout your body, can impact certain blood tests.
How Does a Cold Affect a Blood Test?
A CBC or complete blood count measures many aspects of your blood. They include:
- White blood cells
- Red blood cells
- Hematocrit
- Hemoglobin
- Platelets
A CBC is often ordered as routine bloodwork to measure your baseline levels for these essential blood components. However, it may also be ordered to diagnose disorders of the blood like anemia or those that reveal themselves in blood markers such as leukemia. This is the main blood test that can be affected by a cold. The reason is that in response to a cold, your body produces high levels of neutrophils and low levels of lymphocytes. Both of these can affect the numbers measured by a CBC.
Neutrophils are the white blood cells that the body uses to fight infection, whether caused by viruses or bacteria. These levels will naturally increase while your body fights a cold, at different levels depending on how long you’ve had it. Since your doctor has no way of knowing precisely how these levels change in your body in response to your sickness, they will have no idea what your true blood counts really are.
Lymphocytes are another type of white blood cell designed to prevent infections rather than fight those you already have. Their levels will be naturally low during a cold, which will also change your CBC results.
What Can I Do About a Cold?
If you have a cold and you have a blood test coming up, you may need to reschedule. Colds typically last 7-10 days and are worst during the middle 3-4 days. While you have a cold, you can expedite your recovery with a few easy steps:
- Rest
- Hydrate
- Moisturize your air
- Use OTC remedies
- Eat an anti-inflammatory diet
- Take warm baths
These steps may make you feel better, but they may not be enough to recover from your cold in time for your blood test. You will likely need to reschedule to ensure that the results are accurate.
The Takeaway
A blood test like a CBC measures important blood chemistry that your doctor will use to diagnose certain conditions and manage your long-term care. Having a cold increases and decreases the levels of certain cells, which means that a blood test too close to your infection can impact your results.
Just as you wouldn’t eat before a test that requires fasting, you shouldn’t have a cold during a test that requires your blood counts to be measurable at their baseline. Speak with your doctor about whether your scheduled tests will be impacted by a cold and take their advice to avoid having to repeat the test.
Speedy Sticks is a mobile concierge phlebotomy service that provides at-home blood draws and on-site diagnostic/health screenings for businesses and individuals. These include blood tests, which can be performed by one of our specialists. Book an appointment today to complete your exam.
*This content is for informational purposes only and is not meant to replace consulting with a healthcare professional. Please consult with your primary care physician or healthcare provider before engaging in any services offered by Speedy Sticks.
**These are approximations, and experts disagree on some values. Consult your healthcare provider for recommendations suitable for you. It is also important to ensure the levels are given in the same measurements, such as mg/dL, etc.
