Your cardiovascular system is made up of the heart, blood vessels and blood. Your heart acts as a pump to move blood through blood vessels and to the organs of the body. When blood returns from the tissues it is pumped to the lungs where red blood cells unload carbon dioxide and take up oxygen.

In addition to providing oxygen and removing carbon dioxide from the body, your cardiovascular system helps to maintain pH, temperature, deliver nutrients and remove waste products. Because of its important role as a delivery system the blood contains markers that are used as measurements of health. The levels of blood markers change over time but each has a range of values that can be used to assess cardiovascular health and help to diagnose illness. These markers are important to test because changes often occur before disease develops and detecting changes early allows for modifications to the diet or treatments to reduce the risk of disease.

Biomarkers Include

Total Cholesterol

Normal Range: <200 mg/dL, optimal1,2,3,4; 200-239 mg/dL, borderline high5; >240 mg/dL, high5 

Cholesterol is a waxy, fat-like substance that is critical for a number of functions in the body. It is used to build cell membranes which act as a protective barrier to control what enters and exits the cell. Cholesterol is also an important building block in the synthesis of hormones and other molecules that regulate body systems.

Some cholesterol comes from the diet, but all the cholesterol that you need is made by the liver6. Excessive levels of cholesterol can be used to make a substance called plaque. Plaque is a fatty deposit that sticks to blood vessel walls. As plaque grows it decreases blood to flow through the vessel and starves the tissue of needed oxygen and nutrients. Plaques can weaken and break off the blood vessel wall. They flow through the blood vessels until they get stuck and block the flow of blood. When blood flow to the heart muscle is reduced by plaque this can cause angina or a heart attack. In the brain it causes an ischemic stroke.

Cholesterol levels rise naturally as people age. Cholesterol can become excessive if there is a mutation in a gene that regulates cholesterol levels in the body. This condition is called hypercholesterolemia. Cholesterol levels can also become too high if a diet is high in trans and saturated fats. There are usually no signs or symptoms of high cholesterol levels1. Cholesterol can be decreased by eating a balanced diet that is low in cholesterol as well as trans and saturated fats, exercising, maintaining a healthy body weight, or medications prescribed by a physician7. 

Low Density Lipoprotein (LDL) Cholesterol

Normal Range: <100 mg/dL, optimal2,4,7; 100-129 mg/dL, near-optimal (only a concern with heart disease or other risk factors)1; 130-159 mg/dL, borderline high if no risk factors, high if risk factors are present1; 160-189 mg/dL, moderately high7; >190 mg/dL, extremely/very high7 

LDL is a molecule in the blood that carries cholesterol (LDL-C). High levels of LDL-C are a major risk factor for atherosclerosis. LDL-C can build up on the walls of blood vessels and contribute to plaque formation. Atherosclerosis is the narrowing of arteries due to the build-up of fatty blacks on the vessel walls.

While the upper limit for normal levels of LDL-C is 100 mg/dL it is generally considered that lower LDL-C levels are better for cardiovascular health7. In adults (40 to 75 years of age) with diabetes, chronic kidney disease, coronary artery disease or chronic inflammatory disorders, levels of LDL-C should be below 70 mg/dL because of the increased risk for cardiovascular disease that is associated with these conditions1,7.

High Density Lipoprotein (HDL) Cholesterol

Normal Range: >60 mg/dL, optimal2; 50-59 mg/dL women or 40-59 mg/dL men, good1; <50 mg/dL women or <40 mg/dL men, poor1

HDL-C is called “good” cholesterol because it carries LDL-C to the liver for removal and decreases the risk of atherosclerosis1,5.

Non-HDL cholesterol

Normal Range: <130 mg/dL, optimal; 130-159 mg/dL, near optimal; 160-189 mg/dL, borderline high; 190-219 mg/dL, high; >220 mg/dL, very high8 b

Cholesterol is carried in the blood by high-density lipoproteins (HDL-C), low-density lipoproteins (LDL-C) and very low-density lipoproteins (VLDL-C). Higher levels of LDL-C and VLDL-C increase the risk for cardiovascular disease, while higher levels of HDL-C lower the risk. Non-HDL cholesterol is calculated by subtracting the levels of HDL-C from total cholesterol levels. The higher the value the higher the risk of cardiovascular disease.

Cholesterol-HDL ratio

Normal Range: <5.0

This number is calculated by dividing the total amount of cholesterol by the amount of HDL. A higher number indicates a higher risk of heart disease.

Triglycerides

Normal Range: <150 mg/dL, optimal4; 150-199 mg/dL, borderline high; 200-499 mg/dL, high; >500 mg/dL very high1,5

Excess dietary calories are converted into triglycerides which are stored in fat cells1. Triglyceride levels rise with obesity, diabetes, excessive alcohol intake, lack of exercise, and smoking1. Higher levels of triglycerides indicate a higher risk for cardiovascular disease.

C-Reactive Protein (CRP)

Normal Range: <1 mg/dL, low risk; 1-3 mg/dL moderate risk; >3 mg/dL high risk; >10 mg/dL may indicate a cardiac event like a heart attack9

C-Reactive Protein (CRP) is made by the liver. Levels rise in response to inflammation. Some cardiovascular diseases like atherosclerosis involve inflammation and are associated with increased CRP. CRP levels increase in people with diabetes, high cholesterol, obesity, and smokers9.

There are no standard levels for CRP but ranges of CRP concentrations have been linked to risk of cardiovascular disease10. Increased levels of CRP occur with a variety of conditions, which means elevated CRP may not necessarily reflect cardiovascular risk. Values should be interpreted in combination with other blood markers.

Homocysteine

Normal Range: <15 mM/L, optimal; 15-30 mM/L, moderate; 30-100 mM/L, intermediate; >100 mM/L, severe11

Homocysteine is an amino acid that is produced with breakdown of the amino acid methionine. Levels increase with vitamin B-12 and folate deficiencies. Increased homocysteine is associated with an elevated risk of atherosclerosis, blood clots, heart attack, coronary artery disease, and stroke11. By itself, increased homocysteine is not considered a major risk factor for cardiovascular disease.

References

  1. Mayo Clinic. Cholesterol test. www.mayoclinic.org
  2. CDC. Getting your cholesterol checked. www.cdc.gov/cholesterol/cholesterol_screening.htm
  3. Cleveland Clinic. Cholesterol Guidelines and Heart Health. my.clevelandclinic.org/health/articles/16866-cholesterol-guidelines-heart-health
  4. Harvard. Making sense of cholesterol tests. www.health.harvard.edu/heart-health/making-sense-of-cholesterol-tests
  5. Lab Test Online. Lipid Panel. labtestsonline.org/tests/lipid-panel
  6. AHA. Control your cholesterol. www.heart.org/en/health-topics/cholesterol/about-cholesterol
  7. AHA. Cholesterol Management Guide for Healthcare Practitioners. 2018. www.heart.org/cholesterol
  8. Mayo Clinic. Cholesterol ratio or non-HDL cholesterol: Which is most important. www.mayoclinic.org
  9. Nabili SN. C-Reactive Protein (CRP) Blood Test Chart Ranges. 2020.
  10. Nehring SM et al. C Reactive Protein. NCBI Bookshelf. 2020.
  11. Falck S. High Homocysteine Level (Hyperhomocysteinemia). www.healthline.com