How to read adult laboratory reference ranges
Reviewed on: 29 August, 2026
Laboratory reference ranges describe results commonly seen in a selected reference population. This tool helps you compare one adult result with a compact set of commonly used ranges for hematology, electrolytes, chemistry, coagulation, lipids, endocrine tests, and urinalysis.
How to use this tool
Select the sex used by the reference range, choose a test type, select the test shown on your report, and enter the numeric result in the same unit. The result card identifies whether the number is below, within, or above the general interval. If your report uses another unit, do not enter it until a clinician or laboratory has confirmed the conversion.
What the comparison means
Within this range means the value falls between the displayed limits for this educational comparison. Below or above does not identify a disease: hydration, timing, fasting, exercise, pregnancy, altitude, medicines, symptoms, and measurement method can all matter. A clinician interprets patterns across multiple tests rather than one number in isolation.
Compare carefully
Use the reference interval printed beside your own result whenever it is available. Two laboratories can use different analyzers and populations, and ranges can differ by sex, age, specimen type, and clinical purpose. Keep the date, unit, specimen, and laboratory name with any result you discuss.
Limitations and safety
This tool is not a diagnostic device and does not replace a medical history, examination, repeat testing, or professional advice. It covers selected numeric adult values only; pediatric, pregnancy, therapeutic-drug, critical-care, and disease-specific intervals may be different. Do not change a medicine, supplement, diet, or treatment from this comparison.
When to contact a clinician
Contact the ordering clinician when a result is unexpected, repeatedly outside the report range, changing quickly, or accompanied by symptoms. Seek urgent help for severe breathing difficulty, chest pain, fainting, confusion, heavy bleeding, severe weakness, or any laboratory result your care team labels critical.
What these items mean
The fields and results use established laboratory conventions rather than a single universal standard.
- Reference range
- A reference interval is a comparison window derived by a laboratory or reference source for a defined population. It is not the same as a diagnostic threshold and commonly covers about 95% of a reference group.
- Sex-specific range
- Some adult results differ by sex because physiology and the reference population differ. Use the category that matches your report and ask the laboratory when its report uses another convention.
- Units and methods
- Units such as mmol/L, mg/dL, g/dL, %, and U/L describe amount, concentration, proportion, or enzyme activity. The reporting laboratory’s method and unit are authoritative for your result.
Further reading
For plain-language blood-test context, see the National Heart, Lung, and Blood Institute blood-test guide and MedlinePlus laboratory tests. These links provide education, not a personal diagnosis.