Activated Partial Thromboplastin Time (aPTT) levels: what's normal, high and low
How long it takes blood to clot via the intrinsic pathway. Used to monitor heparin therapy and screen for clotting disorders.
Medically reviewed by Youmna DiStefano, MD · Last reviewed September 2026
The short answer
Activated Partial Thromboplastin Time (aPTT) is measured with a standard blood draw; no fasting is needed. A typical reference range is 25.0 – 35.0 seconds. At TestWell it's $54.99 all-in as PT and PTT (Prothrombin & Partial Thromboplastin Time), results in 1–3 business days, drawn at Labcorp. An out-of-range result is a prompt to look closer, not a diagnosis.
- Units
- seconds / sec
- Sample
- Blood draw
- Fasting
- Not required
- Results
- 1–3 business days
- Price
- $54.99
- Labs
- Labcorp
Activated Partial Thromboplastin Time (aPTT) Reference Range
These are the typical adult reference ranges used by major US labs. Your report will include the specific range used by the lab that processed your sample.
| Population | Range |
|---|---|
| age 18+ | 25.0 – 35.0 seconds |
Reference ranges are educational. Always interpret your result with the specific range printed on your lab report and discuss anything outside the range with a clinician.
What your Activated Partial Thromboplastin Time (aPTT) result may mean
Often reflects heparin therapy, factor deficiencies, or specific clotting inhibitors.
What a high Activated Partial Thromboplastin Time (aPTT) means: causes, symptoms, next steps →Educational only — not a diagnosis. Many factors can influence a single result. Discuss anything that concerns you with a healthcare provider.
How do you get a Activated Partial Thromboplastin Time (aPTT) test?
Order online, a licensed physician reviews the requisition, and you walk into a nearby lab for the draw. Activated Partial Thromboplastin Time (aPTT) is available on its own or inside these panels — panels cost less per marker when you want the fuller picture.
| Option | Includes | Price |
|---|---|---|
| PT and PTT (Prothrombin & Partial Thromboplastin Time) | This marker only | $54.99 |
Quest vs. Labcorp for Activated Partial Thromboplastin Time (aPTT): which lab should you pick?
Both are CLIA-certified national labs and the result is clinically equivalent, so pick whichever location is closer. Your report will print that lab's own reference range, which can differ slightly from the table above.
| Lab | Available | Price |
|---|---|---|
| Quest Diagnostics | No | — |
| Labcorp | Yes | $54.99 |
| BioReference (NY & NJ) | No | — |
Need help choosing a location? Use the lab finder to see draw sites near your ZIP.
Frequently asked
Often reflects heparin therapy, factor deficiencies, or specific clotting inhibitors. A single result above the reference range is a prompt to look closer with a clinician — often a repeat test and related markers — not a diagnosis on its own.
Ready to test your activated partial thromboplastin time (aptt)?
Order in two minutes, get physician-approved, and visit a lab the same day. Starts at $54.99.