Blood work basics: What those tests actually mean

When your blood work results hit your patient portal, it can look like a confusing mix of numbers, medical terms and abbreviations. To help sort it out, we asked Varun Thapar, MD, a family medicine physician with Atlantic Health, to break down the most common tests — and why they are important for your health.

Complete blood count (CBC)

What it checks: Red and white blood cells, hemoglobin and platelets.

Why it’s done: “This helps us detect anemia (a lack of healthy red blood cells), infections or blood disorders,” says Dr. Thapar.

How often it’s ordered: Doctors usually order this test annually — or more often if you have chronic conditions such as chronic kidney disease or autoimmune disorders. Those undergoing chemotherapy or taking medications like blood thinners may need more frequent testing, as do pregnant women.

Comprehensive metabolic panel (CMP)

What it checks: Electrolytes like sodium and potassium, kidney function, liver enzymes and blood sugar.

Why it’s done: It shows how well your organs are working and can catch kidney or liver problems early. “It also helps us monitor for side effects from medications, including statins, seizure drugs and even weight-loss medications (GLP-1s),” explains Dr. Thapar.

How often it’s ordered: It is generally ordered as part of an annual lab workup. Those on statins, seizure medications or GLP-1 medications may need more regular testing based on their medications and individual medical history.

Hemoglobin A1C

What it checks: Your average blood sugar over the last three months.

Why it’s done: This test helps flag prediabetes and diabetes and assists those with diabetes in better managing their blood sugar.

How often it’s ordered: At-risk patients, like those who are overweight, have high blood pressure or a family history of diabetes, usually get tested annually. People with diabetes are typically checked every three months to keep their blood sugar on track.

Lipid panel

What it checks: LDL (“bad” cholesterol), HDL (“good” cholesterol) and triglycerides.

Why it’s done: These numbers indicate your risk of heart disease. “They help us decide whether diet and lifestyle changes are enough or if medication may be needed to reduce the risk of heart attack and stroke,” says Dr. Thapar.

How often it’s ordered: Individuals with risk factors, including diabetes, high blood pressure, obesity, smoking or a family/personal history of heart disease, may need testing every 6 to 12 months.

Thyroid function

What it checks: Thyroid hormones such as TSH (thyroid-stimulating hormone).

Why it’s done: The thyroid influences weight, mood, energy and even heart health. Testing can uncover whether a sluggish or overactive thyroid is the cause of symptoms like fatigue, hair loss or depression.

How often it’s ordered: Thyroid testing is recommended for patients with symptoms or if risk factors are present — such as family history of thyroid disease, certain autoimmune diseases, prior neck radiation or being a woman over 50. Those with thyroid disease or thyroid cancer patients require more routine testing based on their individual condition.

Beyond the numbers

“Lab results are a guide, not the whole story,” says Dr. Thapar. “You know your body best. If something feels off — even if your labs look ‘normal’ — talk to your doctor. We look at both the numbers and how you’re feeling. It’s never just black and white.”

And if you see a red highlight on your portal? Don’t rush to Google. “Red doesn’t always mean bad,” Dr. Thapar adds. “Wait for your provider to explain what it means in your case.”

Blood tests, along with your annual physical, are some of the easiest ways to monitor your health. They can reveal problems early, track how your body responds to medications and help prevent more significant issues down the road. But remember: numbers aren’t the whole story — you are.