Palmetto Preventive
Laboratory test

INR / PT

Evaluates blood clotting time.

About this test

Prothrombin time and INR measure part of the blood-clotting process.

Common reasons for testing

  • Monitoring warfarin treatment.
  • Clinician-directed evaluation of selected clotting or liver concerns.

These are examples of clinical uses. Your history and symptoms determine whether testing is appropriate.

What to expect

A small blood sample is taken from a vein in your arm. You may feel a brief pinch and have mild bruising. Tell the person collecting your sample if you have fainted with needles or take a blood thinner; keep pressure on the site afterward.

Appointment length

Your visit is expected to take about 15 minutes at our West Ashley location.

Categories

Other Laboratory Testing

Preparation

  • Do not skip or adjust warfarin for the blood draw unless your anticoagulation clinician instructs you.
  • Report your dose, missed doses, new medicines, illness, and major dietary changes. Keep your usual diet rather than changing it for the test.
  • Bring a list of medicines and supplements, including biotin, vitamins, and hormones. Do not stop or change prescribed medicines unless your clinician tells you to.

Instructions for this appointment

  • Please tell our team if you take any blood thinners.

Follow the instructions confirmed for your order. If they differ from the general guidance, contact the team before changing food, fluids, or medicines.

Order requirement

No outside order needed

Understanding your results

  • The target INR depends on the reason for warfarin treatment.
  • INR is not a reliable routine measure of the effect of apixaban, rivaroxaban, or similar medicines.

What happens next?

Ensure the clinician managing anticoagulation receives the result and gives dosing instructions. Do not adjust the dose from the portal value alone.

When to seek care sooner

Uncontrolled bleeding, vomiting blood, black stools, or a significant head injury while anticoagulated needs urgent evaluation.

Sources & further reading

This patient summary draws on published clinical literature and professional guidance. Patient resources are identified separately below. Preparation also depends on your specific order and the collecting laboratory or imaging team.

Content updated October 11, 2026. General education; individual advice comes from your care team.

Transparent pricing

Know the cost before your visit

Palmetto Preventive is a direct-pay service. You will see clear payment terms before your booking is finalized — no surprise lab bill.

Self-pay price

$50.00

One transparent price for this test. Payment terms are presented before your booking is finalized.

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Our pricing promise

Transparent self-pay pricing — you see the price before you book.

No surprise lab bill after your visit.

If testing is not approved, your payment is refunded in full.

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