Understand your blood test results
Plain-language explanations of 129 common lab tests: what each one measures, typical and optimal ranges, what high and low results can mean, and what affects them.
Guides
- Why Quest and Labcorp show different reference ranges for the same testWhat a lab reference range is, why two labs can give different ranges for the same blood test, and how to compare results across labs.
- How to read a Labcorp blood test reportA column-by-column guide to Labcorp lab reports: current and previous results, flags, units, reference intervals, lab codes and footnotes.
- How to read a Quest Diagnostics blood test reportHow to read Quest Diagnostics lab reports and MyQuest printouts: in-range and out-of-range columns, reference ranges, lab codes and notes.
- Blood test units explained: mg/dL vs mmol/L and how to convertConversion factors for common blood tests (glucose, cholesterol, triglycerides, vitamin D, testosterone, A1c and more) between US and international units.
- How to prepare for a blood test to get reliable, comparable resultsFasting, time of day, exercise, biotin, alcohol and illness: what changes blood test results and how to make results comparable over time.
Free tool
Lab report viewer: drop your lab PDFs and see your results side by side and charted. It runs entirely in your browser; nothing is uploaded or saved.