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Routine Blood Tests


Want to track your health? Feel tired most of the time, or don’t feel quite up to your mark? Are you past 30 years of age, or on medication for a health problem? If you answered yes, then you may benefit from a simple lab analysis.

Routine blood work can help assess what’s happening inside your body, how your organs are working, and your current lifestyle. This simple test will help your doctor determine current or potential health problems and enable you to offer treatment advice that will help you make more informed decisions on how to take better care of yourself.

In addition, if you already suffer from a health condition, routine blood work can help your provider monitor your treatment.

Health care providers usually perform routine blood tests as part of regular medical checkups. See below for important information about this practice.

Complete Blood Count (CBC)

Complete blood count is the most common routine blood test ordered by doctors.

What are the key components of a CBC?

Here is an example of key components.

  • Red blood cells (RBCs), which transport oxygen throughout your body
  • White blood cells (WBCs), which fight infection
  • Platelets, which play a role in blood clotting
  • Hemoglobin (Hgb), the oxygen-carrying protein inside RBCs
  • Hematocrit, which is the percentage of your blood per volume packed with RBCs

If your CBC results show a high or low white blood cell count, your doctor may also order a white blood cell count differential. This test measures the percentage of the different types of white blood cells in a sample of your blood. There are five different types of white blood cells. Here are the normal proportions for each type:

  • 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

What can be detected in a CBC?

A CBC evaluates the counts, shapes, sizes, and overall health of RBCs, WBCs, and platelets: Hence, it can help detect conditions like these below:

  • Anemia, a low number of RBCs or a low level of Hgb
  • Infection, as indicated by a rise in WBC count
  • Bleeding disorders, as suggested by a drop in platelet count
  • Inflammation, which causes the WBC count to increase
  • Bone marrow suppression, such as by cancer, causes a drop in all the cell lines (RBCs, WBCs, and platelets)
  • Blood cancers, such as leukemia, cause a rise or a drop in the WBC count, depending on whether they are acute or chronic
  • Allergies cause the eosinophil and basophil counts to surge
  • Autoimmune diseases

Basic Metabolic Panel (BMP)

A Basic Metabolic Panel assesses your kidney function, blood sugar, and fluid and electrolyte balance. This test tells your health care practitioner about your body’s acid-base balance and metabolism.

Your doctor can also use the BMP test to monitor you for side effects of certain medications, such as deranged kidney function from pain medicines.

What are the key components of a BMP?

A BMP is a group of 8 tests:

  • Glucose (your blood sugar)
  • Calcium (a major mineral in your bones and teeth)
  • BUN/blood urea nitrogen (a measure of your kidney function)
  • Creatinine (also a measure of your kidney function)
  • Sodium (one of the most important electrolytes)
  • Potassium (the electrolyte found in bananas)
  • Bicarbonate (measures the amount of carbon dioxide in your blood)
  • Chloride (also a mineral)

Glucose is the main fuel for your body. Too little or too much of it indicates a serious problem. High glucose levels may indicate diabetes. The blood glucose test can be done with or without fasting.

Calcium. Low levels can reflect inadequate calcium in your diet, vitamin D insufficiency, under-active parathyroid glands, or other causes. High levels can be due to excessive vitamin D supplementation, overactive parathyroid glands, kidney problems, or other causes.

BUN. Urea is a waste product that exits your body through the kidneys. High levels in your blood are inevitably a sign of kidney damage.

Creatinine is a waste product that your kidneys send in urine. High levels signal kidney failure or muscle disease (creatinine is a byproduct of muscle metabolism).

Sodium mostly comes from your diet and filters out your kidneys in urine. Abnormal levels indicate a problem with your blood osmolality. Blood osmolality is the concentration of particles in your blood and can be affected by diarrhea, excessive fluid intake, or other factors.

Potassium. This electrolyte also comes from your diet and leaves your body through your kidneys. Hence, inadequate kidney function will cause potassium to rise in your blood. In contrast, reduced intake, diarrhea, and other factors, will cause it to drop.

Bicarbonate testing gives information about your body’s acid-base balance.

Chloride helps regulate your body’s acid-base balance.

Comprehensive Metabolic Panel (CMP)

A comprehensive metabolic panel conveys information about your body's fluid and electrolyte balance, total protein levels, and how well your kidneys and liver are working.

What are the key components of a CMP?

A CMP resembles the BMP except that it entails 6 more tests in addition to the 8 parameters of the BMP. The additional six parameters in a CMP include:

  • Total protein (measures the total proteins, namely albumin and globulin)
  • Albumin (a protein made by your liver)
  • Bilirubin (a yellowish pigment formed from the breakdown of red blood cells)
  • Alkaline phosphatase (ALP)
  • Alanine transaminase (ALT)
  • Aspartate aminotransferase (AST)

Albumin. Liver damage will cause your albumin level to fall. Healthy kidneys prevent albumin from passing into the urine. In the setting of kidney damage, this protein will enter the urine, causing its blood levels to drop.

Bilirubin. Excess bilirubin leaves your body through the liver; therefore, liver damage or disease will cause the bilirubin levels to increase. Doctors may check bilirubin levels as part of a CMP or as a component of liver function tests.

Liver enzymes. Elevated liver enzymes are usually a sign of liver damage or inflammation (Hepatitis). However, mild elevations in liver enzyme levels are most often normal fluctuations.

Lipid Panel (Lipid Profile)

A lipid panel test analyzes the levels of fat molecules called lipids in your blood. Clinicians order this test to evaluate the risk of cardiovascular (heart and blood vessel) diseases such as angina, heart attack, and stroke.

What are the components of a lipid panel?

A lipid panel measures three different types of cholesterol and triglycerides. Its components include:

  • Total cholesterol
  • Low-density lipoprotein (LDL) cholesterol
  • High-density lipoprotein (HDL) cholesterol
  • Triglycerides

Total cholesterol evaluates your overall cholesterol level.

LDL cholesterol is also known as “bad cholesterol.” It can build up in your blood and blood vessels, putting you at risk of heart disease. High levels of LDL cholesterol are not healthy.

HDL cholesterol is also called “good cholesterol.” It helps remove LDL cholesterol from your body, thus keeping your blood vessels patent. High levels of HDL cholesterol are healthy.

Triglycerides. These fat molecules come from the excess calories you eat or drink. High levels can lead to heart disease and inflammation of the pancreas.

How to perform a routine blood test?

  1. A healthcare professional first inserts a needle into a vein of your arm or hand.
  2. After drawing blood from your vein, it is collected in test tubes.
  3. The technician/nurse then sends the test tubes to a lab.
  4. Your doctor then reviews your results, and how they compare to the lab’s reference ranges.

How to prepare for a blood test?

Whether or not you need any preparation depends on the test performed. A CBC test, when done alone, doesn’t require any special preparation. However, you will be asked to fast if your test orders include a lipid panel. The Centers for Disease Control and Prevention (CDC) recommends 8 to 12 hours of fasting before a lipid panel.

Do not stop taking medication unless your doctor asks you to.

How often should I get routine blood work?

Routine blood monitoring has no proven value if you’re young, healthy, and have no symptoms.

In the absence of symptoms, the only recommended routine blood work includes:

  • CBC and BMP every year at your annual wellness visit
  • Lipid levels every 5 years (in men ≥ 40 and women ≥ 50)
  • Lipid levels at ≥ 20 years of age every 5 years (if you are at low risk for heart disease).
  • Lipid levels more frequently than every 5 years (if you are at high risk for heart disease).
  • Hemoglobin A1c levels (if you have a risk of developing diabetes), with the frequency depending on the risk

References

Dean, L. (2005). Blood Groups and Red Cell Antigens [Internet]. Bethesda (MD): National Center for Biotechnology Information (US). Chapter 1, Blood and the cells it contains.

Tigner A, Ibrahim SA, Murray I. [Updated 2021 Nov 19]. Histology, White Blood Cell. In: StatPearls [Internet]. Treasure Island (FL): StatPearls

Bertschi L. A. (2020). Abnormal Basic Metabolic Panel Findings: Implications for Nursing. The American journal of nursing, 120(6), 58–66. https://doi.org/10.1097/01.NAJ.0000668764.99872.89

Gounden, V., Vashisht, R., & Jialal, I. [Updated 2022 Apr 4]. Hypoalbuminemia. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing

Lala, V., Goyal, A., & Minter, DA. [Updated 2022 Mar 19]. Liver Function Tests. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing

Centers for Disease Control and Prevention. How and When to Have Your Cholesterol Checked.

Lee Y, Siddiqui WJ. [Updated 2021 Jul 26]. Cholesterol Levels. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing

Shaked, M., Levkovich, I., Adar, T., Peri, A., & Liviatan, N. (2019). Perspective of healthy asymptomatic patients requesting general blood tests from their physicians: a qualitative study. BMC family practice, 20(1), 51. https://doi.org/10.1186/s12875-019-0940-9

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