Blood Tests Your Doctor May Order and What They Mean
Last updated: June 2022
Doctors often order blood tests which requires that you have your blood drawn. The information obtained from your blood can be helpful to doctors. It can help them monitor how you are doing over time and can also help guide them on how to best manage your health. Here are some common blood tests doctors order along with normal ranges and what they mean.
Note: I obtained the normal ranges from Spectrum Health. This is the health system that I work for.
What can blood tests measure?
Red Blood Cells (RBC)
They are cells that carry hemoglobin. Oxygen binds with hemoglobin. So, they are cells that carry oxygen in your blood. A normal range is 4.60 - 6.00 10*6/uL.
- Low: This indicates anemia. This may be due to bleeding. It may also be due to various disease processes, such as chronic kidney disease.1,2
- High. This is a condition called polycythemia. Some people with COPD may have chronically low blood oxygen levels (hypoxemia). When this happens long term, your body may try to compensate for this by creating more RBCs.1,3
White Blood Cells (WBC)
They are elevated when you have an infection. A normal range is 4.00 - 10.80 10*3/uL.
- Low. May indicate a reduced ability to fight off infections.1
- High. May indicate that you have a bacterial infection. People with COPD may have an increased risk of developing pneumonia. Pneumonia is usually caused by bacteria. For this reason, your doctor may want to keep an eye on your WBC count.1,4
The most abundant WBC. A normal range is 5.0 - 80.0 %.1
- Low. It's called neutropenia. It may indicate your body is less capable of fighting infections.5
- High. This may indicate you have a bacterial infection, such as pneumonia.6
They are another WBC. A normal range is 0.0 - 6.0 %. A high level may indicate allergies.1 It may also indicate eosinophilic asthma.
It's a protein in RBCs that binds with oxygen molecules. It carries oxygen in your blood. A normal level is 14.0 - 18.0 g/dL.
- Low. It may indicate your blood has a decreased ability to carry oxygen to tissues. A potential cause may be anemia, which means loss of blood.
- High. Various conditions may cause this. Sometimes severe COPD may cause it. This happens only if your oxygen levels are chronically low. Your body may try to compensate for this by creating more hemoglobin.1
This is a measure of the proportion of RBCs in your blood. A normal range is 42.0 - 52.0 %.
- Low. May indicated anemia. This may be due to blood loss. It may be due to some other health condition.1
- High. May indicate dehydration. You need fluids. You need to drink more water.1
Blood Urea Nitrogen (BUN)
Urea is made by your liver and leaves your body in urine. It shows how well your kidneys are working. A normal range is 8 - 20 mg/dL. If your kidneys are not working right they may become ineffective at getting rid of it. This can cause your BUN to become elevated and an elevated BUN may indicate problems with your kidneys, such as kidney failure. It may also indicate heart failure or dehydration.
Like BUN, it can show how well your kidneys are working. Creatine is a waste product. It is made when your body makes energy out of the food you eat. It is filtered from your blood by your kidneys. So, if creatinine levels are high, this may indicate kidney problems, such as kidney failure.9
It comes from the food you eat and is used by cells to make energy. When you eat, your glucose levels rise. When this happens, your pancreas releases insulin which helps to keep your glucose levels normal. A high glucose level may indicate diabetes. People with COPD may be at an increased risk for diabetes so this is something your doctor may want to monitor.10
There is a lot of other information your doctor can obtain from your blood. What they want to measure may depend on the symptoms you are experiencing. For example, if you are having chest pain, your doctor may order a troponin level. Troponin is a protein secreted by your heart when it has undergone some damage. This can indicate your heart isn't getting enough oxygen, potentially due to a severe COPD flare-up it may also show if you are having a heart attack.10
More than just the lungs
COPD may have an impact on more than just your lungs. For this reason, it is important for doctors to monitor how your other organs are doing. Most doctors will order blood tests on a regular basis, although if I make unscheduled doctor visits or need to use the ER, I may have my blood drawn more often.
Do you know the difference between a COPD exacerbation and lung function decline?
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