How to Read Your Blood Test Results: A Complete Guide

Why Your Lab Report Looks Confusing

When your doctor orders blood work, you typically receive a printout or portal notification filled with abbreviations, numbers, and flags like "H" (high) or "L" (low). Most patients leave the office without a clear explanation of what these figures actually mean for their health. This guide demystifies the four most commonly ordered blood panels.

The Complete Blood Count (CBC)

The CBC is a snapshot of the three main cell types in your blood: red blood cells, white blood cells, and platelets. Your lab report will list values such as WBC (white blood cell count), RBC (red blood cell count), hemoglobin (Hgb), hematocrit (Hct), MCV (mean corpuscular volume), and platelet count. Reference ranges vary slightly between laboratories, but a typical adult WBC range is 4.5–11.0 × 10⁹/L.[2] Hemoglobin normal ranges are approximately 13.5–17.5 g/dL for men and 12.0–15.5 g/dL for women.

An elevated WBC can indicate infection, inflammation, or in rare cases, a blood disorder. A low hemoglobin level is the hallmark of anemia, which can stem from iron deficiency, vitamin B12 deficiency, or chronic disease. Your doctor interprets these values together rather than in isolation.

The Comprehensive Metabolic Panel (CMP)

The CMP provides a window into your kidney function, liver health, electrolyte balance, and blood glucose. It includes 14 measurements: glucose, calcium, sodium, potassium, bicarbonate, chloride, BUN (blood urea nitrogen), creatinine, eGFR (estimated glomerular filtration rate), total protein, albumin, bilirubin, alkaline phosphatase (ALP), AST, and ALT.

Fasting glucose between 70–99 mg/dL is considered normal. A value of 100–125 mg/dL signals prediabetes, while 126 mg/dL or higher on two separate tests meets the diagnostic threshold for type 2 diabetes. Creatinine and eGFR together reflect how well your kidneys filter waste—an eGFR below 60 mL/min/1.73 m² suggests chronic kidney disease.

The Lipid Panel

Cardiovascular risk assessment relies heavily on the lipid panel, which measures total cholesterol, LDL cholesterol ("bad"), HDL cholesterol ("good"), and triglycerides. Optimal LDL is below 100 mg/dL, though people with existing heart disease often target below 70 mg/dL. HDL above 60 mg/dL is considered protective. Triglycerides should ideally remain below 150 mg/dL.

The ratio of total cholesterol to HDL is also informative. A ratio below 4.0 is generally favorable. Your doctor may use a 10-year cardiovascular risk calculator alongside these numbers to decide whether lifestyle changes or medication are appropriate.

The Thyroid Panel

Thyroid function tests typically include TSH (thyroid-stimulating hormone), free T4 (thyroxine), and sometimes free T3 (triiodothyronine). TSH is the most sensitive marker and is usually tested first. A normal TSH range is approximately 0.4–4.0 mIU/L, though laboratories may differ slightly.[4] A high TSH with a low free T4 suggests hypothyroidism; a low TSH with a high free T4 points toward hyperthyroidism.

Symptoms of thyroid dysfunction—fatigue, weight changes, cold intolerance, or palpitations—often prompt thyroid testing. Because TSH can fluctuate with illness or certain medications, a single abnormal result is usually confirmed with repeat testing before initiating treatment.

How to Use Your Results

Always view your results in context. A single number outside the reference range is not automatically cause for alarm. Reference ranges represent the central 95% of healthy individuals, meaning 5% of healthy people will have at least one value outside the range by chance.[1] Trends over time, your symptoms, and your personal history all matter.[3] Use tools like the Health3 app to track values across visits and surface meaningful patterns.

Track Your Biomarkers With Health3

Scan your lab results, explore biomarker interactions, and track trends over time with the Health3 app.