Breaking Down Your Blood Test

Clinical testing plays an important role today in how physicians diagnose illness and create treatment plans. New advancements in technology and medicine have improved clinical testing accuracy while reducing costs and risk. These improvements have also made certain tests more widely available. Today, modern medical professionals rely on tests to help us understand what is happening with our patients more fully, in addition to performing physicals and reviewing patient health history.

Medical providers generally try to reduce unnecessary testing as much as possible. However, I don't predict that basic laboratory testing for blood will decrease in a significant way. You will probably be asked to perform a basic blood panel at some point in your medical history. A blood panel is a type of test often requested by providers, and the results can be confusing to patients who may not know how to interpret the results!

Below, we'll review the most common tests and provide a brief explanation of how to read your results.

Complete Blood Count or CBC

The complete blood count is a common test that often comes with cell differentiation. It can help physicians recognize infection and cancer if the white blood cell count is too high or too low. It can also detect anemia based on red blood cell count. The test is also used to measure hemoglobin and the ability of the blood to clot based on the platelet count, which can be elevated or diminished.

In general, the white blood cell count should be between three and 12. Hemoglobin for women should be greater than 12, and greater than 14 for men. Platelet count should be greater than 150 on testing.

Complete Metabolic Profile or CMP

The main components of this test show electrolyte balance in form of sodium (NA), chloride (CL) and potassium (K) which have many implications. A fasting sample can help us determine glucose or sugar problems if the figure is greater than 100.

In addition, creatinine (Cr) and blood urea nitrogen (BUN) are important factors in determining hydration status and how the kidneys are doing. This leads to a glomerular filtration rate (GFR) that indicates if the kidney is suffering from chronic kidney failure. The panel also looks at the liver functions with bilirubin, AST/ALT and alkaline phosphate which can detect early signs of fatty liver change or damage from medications.

Urinalysis or UA

This common test assesses the hydration of the patient through the specific gravity of the urine and possible abnormalities based on color and pH. However, the main purpose is to check leukocytes or nitrites for infections, glucose for possible diabetes and protein and blood for possible early cancers or signs of kidney disease.

Thyroid Studies (TSH, Free T3, T4 and others)

These tests seek to detect thyroid abnormalities. Elevated T3 and T4 will cause the TSH levels to be very low which could be a sign of hyperthyroidism. A low T3/T4 usually leads to elevated TSH and could be a sign of hypothyroidism.

Cholesterol or Lipid Panel

This is a very common test that is often hard to understand. The test is broken down into:

• Total Cholesterol (TC)
• High-density Lipid (HDL)
• Low-density Lipid (LDL)
• Triglycerides
• Total cholesterol to high-density lipid ratio (TC/HDL ratio) 

All of the above figures are important. The greatest factor in risk is the absolute number for low-density lipid. Numbers that are greater than 130 are concerning, while numbers less than 100 are excellent. High-density lipid (HDL) is another very important figure as it protects us from harm from other cholesterol types. Ideally, numbers that are greater than 60 are best, whereas less than 40 is considered abnormal.

Triglycerides are important as they play a role in inflammation and are more closely linked to how we eat. Numbers that are less than 150 are excellent while greater than 500 become truly worrisome. The ratio is very important in assessing risk. A number that is greater than five means that the patient is at an increased risk.

Hemoglobin A1C or A1C

More commonly ordered, this test shows the glucose (sugar) pattern over the past three months. It is a number given as a percentage and can help physicians determine if diabetes is present and if the patient is at risk or normal. A figure greater than 6.5% indicates diabetes, while figures greater than 5.7% and less than 6.5% indicates prediabetes.

Remember that clinical tests are rarely diagnostic of conditions alone. Your provider and healthcare team will always use your medical history and physical along with the clinical course to determine the significance of any lab results. There are always exceptions and good communication and follow up with your healthcare team will lead to improved health.

I hope that this information helps you to better understand your test results to engage with your healthcare teams in achieving the best health outcomes possible!

Editor's note: This article was originally published on April 20, 2015.