Learn to check test names, units, reference intervals and trends, and prepare useful questions for the doctor who ordered your tests.
A blood report can look worrying when several values are printed in bold or marked with an asterisk. Those marks are a starting point for a conversation. Your doctor also considers why the test was ordered, your symptoms, medicines and previous results before deciding what the findings mean. MedlinePlus: Understanding laboratory results
Start with the basics
Check that the report belongs to you and that the sample date is correct. Read each row from left to right: test name, your result, units and the laboratory’s reference interval. Keep the complete report, including comments, rather than saving only the highlighted values.
Units matter. Two results with different units cannot be compared as if they were the same number. Reference intervals may differ between laboratories and between groups such as children and adults. Use the interval on your own report rather than a chart forwarded on WhatsApp. MedlinePlus: Understanding laboratory results
Understand what a flag can and cannot tell you
A value outside the reference interval does not always mean disease. Equally, a result within it does not rule out every health problem. “Positive” usually means the test detected what it was looking for; some positive results need confirmation. An inconclusive result may need repeating. MedlinePlus: Understanding laboratory results
Ask your doctor which findings are important in your case. Avoid counting red marks as a measure of how unwell you are. A report is most useful when someone connects the findings to the reason you were tested.
Think about preparation and recent changes
Some results are affected by food, exercise, medicines or supplements. Tell the doctor about any preparation instructions you could not follow, recent symptoms and everything you take. Honest information helps them decide whether a result needs checking again. Never stop a medicine simply to improve a test result. MedlinePlus: Preparing for a laboratory test
Fast only when instructed. If fasting is required, confirm its length and whether plain water is allowed; water is usually permitted. Tea, coffee, juice and food can affect tests that require fasting. If you accidentally eat or drink, tell the laboratory rather than hiding it. MedlinePlus: Fasting for a blood test
Leave with a clear next step
Blood tests may lead to repeat tests or further investigation. Make sure you know how and when your results will be reviewed. Contact the clinic if the expected review has not happened. NHS: Blood tests and getting your results
- Which result needs attention, and how soon?
- Do my earlier reports change the interpretation?
- Is another test needed, and what would it clarify?
- What symptoms should make me seek help sooner?
Do not let a report delay urgent care
Severe breathing difficulty, chest pain, collapse, sudden stroke-like symptoms or heavy uncontrolled bleeding need emergency help. Seek care even if an earlier report looked reassuring. If a laboratory or clinician contacts you about a critical result, act on their instructions promptly. MedlinePlus: Recognising medical emergencies
Sources and further reading
- MedlinePlus: Understanding laboratory results
- MedlinePlus: Preparing for a laboratory test
- MedlinePlus: Fasting for a blood test
- NHS: Blood tests and getting your results
- MedlinePlus: Recognising medical emergencies
Editorial review and source check: 17 October 2026.
Medical disclaimer: This article provides general health information, not a diagnosis or a treatment plan. A qualified medical professional should interpret your results in the context of your health. Do not start, stop or change medicines based on this article.
© 2026 EndYourIllness. Original text. Third-party names and marks belong to their respective owners.
