aPTT
aPTT measures the speed of clotting via the intrinsic pathway. It is used to monitor certain blood-thinning medications (heparin) and to detect clotting disorders (e.g. hemophilia).
| Rating | Range | What it means |
|---|---|---|
| Talk to a doctor | below 25 s | Shortened — context. |
| Good | 25 – 38 s | Within the reference range. |
| Talk to a doctor | 38 s and above | Prolonged — consult (clotting). |
Why it matters
ISTH: prolonged indicates a clotting disorder or medications (heparin).
If it’s low
A short aPTT is mostly of no significance; rarely it indicates an increased tendency to clot.
If it’s high
Prolonged aPTT means slower clotting — expected with heparin; otherwise possibly a deficiency of clotting factors, liver disease or antibodies.
What to do
aPTT is a hospital/specialist test. With unexplained bleeding or a family history of clotting disorders, arrange work-up with a doctor.
Read together with
INR · Platelets · Fibrinogen
This content is for information only and is not a substitute for medical advice. Talk to your doctor about your results.
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