Here’s how to understand your blood tests

Annual physical examinations are a cornerstone of preventive health care. During a physical exam, your doctor may order routine blood tests to understand your metabolic health, cardiovascular health, and liver and kidney function.  

“These tests give doctors a snapshot of your overall health, allowing for early detection of potential problems and assessing your risk of developing disease,” says Dr. Katie Thompson, an internal medicine physician at Aurora Health Care. “Blood testing is an essential part of your annual physical exam — the same way reviewing your medical history and checking your heart and lungs are.” 

Here are a few common blood tests your doctor may order during your annual physical exam. However, like with all tests, make sure you talk to your physician first to make sure it’s necessary and make sure it’s covered by your insurance.

Complete blood count (CBC) 

The complete blood count is one of the most common blood tests performed. It measures several components of your blood, including red blood cells, white blood cells and platelets. 

• Red blood cells (RBCs): Red blood cells transport oxygen throughout the body. By measuring the number, size, and hemoglobin concentration of red blood cells, your doctor can detect conditions such as anemia, dehydration or other blood disorders. 
• White blood cells (WBCs): White blood cells are one of your body’s defenders against infections. High or low levels of white blood cell counts can indicate an infection, bone marrow disorder or autoimmunity. 
• Platelets: Platelets are essential for blood clotting. Abnormal platelet counts can signal various conditions, including clotting disorders or diseases of the bone marrow. 

Basic metabolic panel (BMP) 

The metabolic panel provides essential information about your heart, kidney and muscle function. It usually includes tests for: 

• Glucose (A1C): A measure of your sugar level, can be used to identify diabetes or prediabetes. 
• Calcium: This checks the health of your bones and ensures your nervous system, muscles and heart are functioning properly. 
• Electrolytes: Often including sodium, potassium, bicarbonate, and chloride, these tests assess heart, nerve and muscle function. 

Lipid panel 

A lipid panel measures cholesterol levels in your blood, including LDL (low density lipoprotein), HDL (high density lipoprotein) and total cholesterol. High cholesterol levels can indicate an increased risk of heart disease. 

• Total cholesterol: A measure of all the cholesterol in your blood. 
• High-density lipoprotein (HDL): Often termed as ‘good cholesterol,’ higher levels of HDL can lower your risk of heart disease. 
• Low-density lipoprotein (LDL): Known as ‘bad cholesterol,’ high LDL levels can lead to plaque buildup in arteries, increasing heart disease risk. 
• Triglycerides: These are a type of fat in your blood. Elevated levels can increase the risk of heart disease, especially if both HDL is low and LDL is high. 

Thyroid function tests 

These tests measure how well your thyroid gland is working. They often include: 

• Thyroid stimulating hormone (TSH): This hormone is produced by the pituitary gland and tells the thyroid to produce hormones. High TSH levels can indicate an underactive thyroid (hypothyroidism), while low levels could indicate an overactive thyroid (hyperthyroidism). 
• T4 (thyroxine): This is a hormone secreted by the thyroid gland. T4 tests help diagnose hyperthyroidism or its severity. 
• T3 (triiodothyronine): This is another hormone produced by the thyroid. Some doctors believe T3 testing is helpful for a more comprehensive understanding of thyroid function, especially when T4 levels don’t offer a clear picture. 

Liver function tests

These tests measure various enzymes and proteins associated with liver health. Abnormalities can indicate liver diseases or damage: 

• Alanine transaminase (ALT): ALT levels increase with liver damage. 
• Aspartate transaminase (AST): AST levels can indicate liver damage when elevated. 
• Albumin: This is the primary protein made by the liver. Low levels might indicate liver disease or other medical conditions, such as malnutrition, liver or kidney disease, or autoimmune disease.  

Kidney function tests 

The kidneys play a crucial role in filtering the blood, removing waste through urine. Tests to ensure kidney health include: 

• Blood urea nitrogen (BUN): Measures the amount of nitrogen in your blood that comes from the waste product urea. Elevated levels might indicate kidney dysfunction. 
• Creatinine: This waste product from muscle metabolism is filtered out of the blood by the kidneys. Elevated levels can be a sign of kidney dysfunction. 

Blood tests offer invaluable insights into your overall health, flagging potential issues before they become major problems. Understanding the types of blood tests your doctor may order can help them provide you with the best care possible. 

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