Partial Thromboplastin Time (PTT)
A screening measure of how fast blood clots through the intrinsic pathway, central to investigating unexplained bleeding or clotting.
Consider this test if:
- Easy bruising, frequent nosebleeds, or bleeding that lasts longer than expected
- A previous coagulation test came back with a prolonged PTT that needs explaining
- Recurrent blood clots, unexplained miscarriage, or a question of lupus anticoagulant
- Assessing bleeding risk before a planned surgery or procedure
- On heparin or another anticoagulant and tracking its effect on clotting
- HSA/FSA eligible
- Typical results in about 7 days · Reviewed by a real clinician
- Drawn at a CLIA/CAP-accredited lab near you ·
Pre-test considerations
No fasting required. Tell the ordering clinician about any anticoagulants (heparin, Factor Xa inhibitors, direct thrombin inhibitors) or recent blood thinners, since these prolong the result and affect interpretation. The sample is citrated plasma that must be processed and frozen promptly, so collection happens at a lab equipped to centrifuge and freeze it.
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What this test is for
The activated partial thromboplastin time (aPTT) measures how long plasma takes to clot through the intrinsic and common coagulation pathways. A prolonged result points to a clotting factor deficiency, a clotting factor inhibitor, an anticoagulant such as heparin, or a lupus anticoagulant, while a shortened result is rarely clinically meaningful. This particular workup goes beyond the screening time: it reflexes into the studies that explain an abnormal PTT, including Factor VIII, IX, and XI activity, mixing studies, and lupus anticoagulant testing (DRVVT and hexagonal phase). It is commonly run to evaluate easy bruising, heavy or prolonged bleeding, recurrent clots, or pregnancy loss, and to assess bleeding risk before surgery.
The related PT/INR plus PTT panel pairs this same aPTT with prothrombin time, which screens the extrinsic pathway and monitors warfarin; this item is the deeper PTT-focused coagulation evaluation rather than a routine two-test screen.
- Specimen
- Platelet-poor plasma
- Method
- Coagulation assay
- Measures
- Time
What you'll learn
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Insights that connect the dots. A clinician reads your whole picture, not one result in isolation, connecting family history, past results, and lifestyle into clear next steps.
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Your personalized action plan. Nutrition, supplements, and training in one clinician-reviewed protocol, updated as your results change.
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Track your trends. Upload results from any lab and see each biomarker trend over time, so you know what is working.
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Never miss a recheck. Mito tells you what is worth retesting and when, then reminds you so nothing slips.
What to expect
- 1 Book instantly
Click, book, done. Choose a convenient lab location near you. Transparent, up-front pricing.
- 2 Quick lab visit
Testing to fit your busy schedule, usually 15 minutes or less. Walk-in and appointments available.
- 3 Typical results in about 7 days
Your results post straight to your dashboard as soon as the lab completes them.
- 4 Expert guidance
Included with Mito membership. A clinician reviews your results and your personalized action plan follows, with clear next steps.
Everything your health needs,
in one membership
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Every test at our cost
Members pay our cost on every test, with lab fees passed straight through. The full receipt is itemized, never padded.
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Continuous tracking, all in one place
Upload past labs and watch your trends over time. Every marker and visit lives in one longitudinal record, so all your care stays together.
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Year-round clinician support
Text anytime and get clinician-reviewed answers. When you want to go deeper, 1:1 consultations are available at affordable rates.
All for $9/month
Order any test or consult without joining. For $9/month, members unlock member prices, trend tracking, and year-round clinician guidance.
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Without membership
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Frequently asked questions
View all FAQsHow does pricing work?
Every test shows the member price next to the standard non-member price, so you can see what membership saves you. The member price is our cost, covering the lab and what it takes to run the service. It is never a profit on the test itself. Mito makes its money on the $9 membership, not on marking up your tests. Membership is $9 per month, and any applicable lab order or draw fee is itemized before you pay.
Where do I get tested?
Choose an available partner lab at checkout. If your cart contains multiple blood tests, Mito helps consolidate the eligible tests at one lab when possible. At-home kits and scans follow the collection or appointment process shown on their product page.
Is this eligible for HSA/FSA?
Yes. Eligible tests can be paid for with an HSA or FSA card at checkout.
When will I get my results?
Your results appear in your Mito dashboard after the laboratory completes processing. A clinician then reviews them before your analysis and personalized action plan are finalized. Timing varies by test, and specialty assays and at-home kits may take longer.
Do I need a physician's order?
No. Mito provides the laboratory order when one is required, so you do not need to arrange a separate physician visit before purchasing.
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