Understanding Your Lab Results

Learn how to read common lab test results, what reference ranges mean, and when to follow up with your doctor.

What Are Reference Ranges?

Reference ranges show the expected values for a healthy population. Results outside these ranges may indicate a potential health issue, but they are not a diagnosis on their own. Factors like age, sex, diet, medications, and activity level can all influence your results.

Common Blood Test Results

Test Typical Normal Range What It Means
Glucose (Fasting) 70-100 mg/dL Blood sugar level after fasting
A1C Below 5.7% Average blood sugar over 2-3 months
Total Cholesterol Below 200 mg/dL Overall cholesterol in blood
LDL Cholesterol Below 100 mg/dL "Bad" cholesterol
HDL Cholesterol Above 40-60 mg/dL "Good" cholesterol
TSH 0.4-4.0 mIU/L Thyroid-stimulating hormone
Vitamin D 20-50 ng/mL Bone and immune health

When to Follow Up

You should always discuss your lab results with a licensed healthcare provider, especially if:

  • Your results are significantly outside the reference range
  • You have symptoms that match abnormal results
  • You are taking medications that may affect test outcomes
  • You have a family history of conditions related to the test

False Positives & False Negatives

No lab test is perfect. False positives suggest a condition exists when it does not, while false negatives miss a condition that is actually present. Repeat testing, additional panels, and clinical evaluation help confirm results.

Medical Disclaimer: WebHealthClinic is an independent health education resource. We do not provide medical advice, diagnosis, or treatment. Always consult a licensed healthcare provider for interpretation of your lab results.