What Does Your Blood Work Mean? A Guide to Understanding Common Lab Results

You get a notification that your lab results are ready. You open the report and see a page full of acronyms, numbers, and H or L flags. Maybe everything looks fine. Maybe several things are flagged and you’re not sure whether to be concerned or not.

Blood work is one of the most powerful tools in preventive medicine, but it’s only useful if you understand what you’re looking at. This guide covers the most common tests ordered in a routine annual physical and what the numbers actually mean.

The Complete Blood Count (CBC)

The CBC is one of the most common blood tests ordered. It measures the different types of cells in your blood and gives a broad picture of your overall health.

Red Blood Cells (RBC) and Hemoglobin/Hematocrit These measure whether you have enough red blood cells to carry oxygen throughout your body. Low values indicate anemia, which can cause fatigue, weakness, shortness of breath, and paleness. High values can indicate dehydration or certain conditions that overproduce red blood cells.

Mean Corpuscular Volume (MCV) This tells you the size of your red blood cells, useful for identifying the type of anemia. Small red blood cells (low MCV) often point to iron deficiency. Large red blood cells (high MCV) can indicate B12 or folate deficiency.

White Blood Cells (WBC) Your immune cells. A high WBC typically indicates your body is fighting an infection, inflammation, or in some cases points to a blood disorder. A low WBC can indicate a viral infection, certain medications’ effects, or immune suppression.

Platelets These help your blood clot. Low platelets (thrombocytopenia) can cause easy bruising and bleeding. Very high platelets can increase clotting risk.

The Comprehensive Metabolic Panel (CMP)

The CMP or basic metabolic panel (BMP) in a shorter version, checks how your organs are functioning and how your body is managing key minerals and fluids.

Sodium, Potassium, Chloride, Bicarbonate (the electrolytes) These maintain fluid balance, nerve function, and muscle contraction. Abnormalities are often linked to dehydration, kidney function, medications, or dietary habits.

Blood Urea Nitrogen (BUN) and Creatinine These are waste products filtered by the kidneys. Elevated levels suggest the kidneys aren’t clearing waste efficiently, a possible sign of kidney disease, dehydration, or medication effects. The BUN-to-creatinine ratio helps your doctor interpret which cause is more likely.

eGFR (Estimated Glomerular Filtration Rate) Calculated from creatinine, this estimates how well your kidneys are filtering. An eGFR above 60 is generally considered normal. Below 60, sustained over time, warrants closer monitoring for chronic kidney disease.

Glucose Your blood sugar at the time of the draw (if fasting) or in the recent hours (if not). Fasting glucose above 100 mg/dL signals prediabetes range; above 126 mg/dL is in the diabetes range if confirmed. This is different from A1C, which reflects a 3-month average.

Liver enzymes (AST, ALT, ALP, GGT) These reflect liver function. Mildly elevated liver enzymes are common and have many causes, fatty liver, alcohol, certain medications, vigorous exercise before the test. Significantly elevated or persistently elevated levels warrant further investigation.

Total Protein and Albumin Proteins produced by the liver, reflecting nutrition and liver function. Low albumin in particular can indicate chronic illness, poor nutrition, or liver or kidney disease.

Bilirubin A breakdown product of red blood cells processed by the liver. Elevated bilirubin can cause jaundice (yellow skin or eyes) and may indicate liver or blood conditions.

The Lipid Panel (Cholesterol)

Covered in detail in our cholesterol post, but briefly:

• Total Cholesterol: ideally below 200 mg/dL
• LDL (“bad” cholesterol): ideally below 100 mg/dL (lower for high-risk individuals)
• HDL (“good” cholesterol): higher is better; ideally above 60 mg/dL
• Triglycerides: ideally below 150 mg/dL

Thyroid-Stimulating Hormone (TSH)

The TSH measures how hard your pituitary gland is working to stimulate the thyroid. It’s an indirect but sensitive measure of thyroid function.

High TSH: The pituitary is working overtime to stimulate an underperforming thyroid. This suggests hypothyroidism (underactive thyroid), which can cause fatigue, weight gain, constipation, feeling cold, and low mood.

Low TSH: The pituitary is dialing back because the thyroid is overproducing. This suggests hyperthyroidism (overactive thyroid), which can cause weight loss, racing heart, anxiety, and heat intolerance.

Normal TSH range: approximately 0.4–4.0 mIU/L, though this varies by lab and individual situation.

Hemoglobin A1C (HbA1c)

As discussed in detail in our A1C post: this reflects your average blood sugar over the past 2–3 months.

• Below 5.7% – Normal
• 5.7–6.4% – Prediabetes
• 6.5% or above – Diabetes (usually confirmed with a second test)

Vitamin D (25-hydroxyvitamin D)

Not always included in a standard panel but frequently ordered. As covered in our vitamin D post:

• Below 20 ng/mL — Deficient
• 20–29 ng/mL — Insufficient
• 30–100 ng/mL — Sufficient

Understanding reference ranges

Every lab result comes with a reference range, the range of values considered normal for that test. These ranges are established by testing large healthy populations and capturing the middle 95% of results. That means 5% of healthy people will fall outside the range even without a problem.

This is why a single flagged value doesn’t automatically mean something is wrong. Your doctor interprets each result in context: your age, sex, symptoms, medications, recent activities, and how the result compares to your previous values over time.

A result that’s mildly outside the range in an otherwise healthy person with no symptoms means something different from the same result in someone with relevant symptoms and a family history.

What to do when something is flagged

Don’t panic, but don’t ignore it either. A flagged result is a prompt to have a conversation with your doctor, not necessarily a cause for immediate alarm.

Ask your doctor to explain it in plain language. What does this specific result mean for me? Is this something we need to act on now, monitor over time, or investigate further?

Understand the follow-up plan. Is a repeat test needed? Should anything change in your diet, medication, or activity? When should you recheck?

Track your results over time. A single number is less informative than a trend. Keeping a personal log of your bloodwork over years gives both you and your doctor a much clearer picture of your health trajectory.

How Beloved Medical can help

We review all lab results with patients in plain language, not just a portal notification that says “within normal limits” with no explanation. If something comes back flagged, we explain what it means, why it matters, and what the plan is.

Annual bloodwork is part of our comprehensive annual physical. It’s one of the most valuable things you can do for your long-term health because it catches problems early, often before they cause any symptoms.

To schedule an annual physical or bloodwork review:

• Call (901) 249-0847
• Or book an appointment online

We accept most major insurance plans. Annual physicals including bloodwork are typically covered as preventive care.

This blog post is for informational purposes only and does not replace professional medical advice. Please consult your healthcare provider to interpret your specific lab results in the context of your individual health.