Coagulation panel: how quickly your blood clots

Blood clots in two steps. The moment a vessel wall is damaged, platelets stick to it and form a first plug within seconds. A cascade of clotting factors then builds a firm fibrin mesh over that plug, so the wound stays closed instead of reopening. When either step runs less smoothly, you usually notice it in ordinary ways.

Bruises turn up without you remembering the knock. Nosebleeds come back more often than they used to. A shaving nick keeps oozing long after it should have stopped. Periods feel heavier than you think they ought to. A coagulation screen looks at both halves of the chain at once, so you are not left guessing which end the problem sits at.

Worth knowing up front: a value just outside the reference range is common, and the explanation is usually mundane. An infection you were getting over, or a difference between laboratories, can be enough on its own. An abnormal result is a reason to have a conversation, not a reason to worry.

This coagulation panel may suit:

• people who bruise more easily, or bleed for longer, than they think they should
• people whose doctor asked for a coagulation screen and who want it done without a referral
• people with a family member who has a known bleeding or clotting disorder
• people with liver disease, since the liver makes almost all of the clotting factors

If you take anticoagulants and want your INR checked so your dose can be adjusted, this is not the panel for you. That monitoring belongs with your anticoagulation clinic, which tracks your value on a fixed schedule and changes your dose directly.

You get four values, two for each half of the clotting chain:

• INR: a standardised measure of how quickly the clotting route that starts outside the vessel completes. That standardisation is what makes results from different labs comparable.
• aPTT: covers the route that starts inside the vessel, and times how long it takes.
• Fibrinogen: the protein the fibrin mesh is built from, the raw material for the layer that sets over the plug.
• Platelets: the cells that form the very first plug.

All four sit in the Coagulation category, where each value is explained in more depth.

A prolonged INR or aPTT points to a clotting factor being low, or to something in the blood slowing the chain down. Which of the two is prolonged narrows down where: INR stands for the route that begins outside the vessel, aPTT for the route that begins inside it. If both are prolonged, the cause is more likely to sit in the stretch the two routes share.

A low fibrinogen or a low platelet count points to the other end of the chain: less raw material to build the mesh with, or fewer platelets to form the first plug.

What this screen does is make the question smaller. It tells you which direction is worth looking in, not what you have. Which follow-up test comes next is a decision a doctor makes, based on your results and your symptoms.

For this panel, blood is drawn from a vein at one of our 700+ certified sample points across the Netherlands. After ordering you pick the location and the time yourself.

Coagulation tests need a citrate tube that has to be filled to the mark and reach the lab quickly, or the values drift. That is why the draw is done by trained staff at a certified location, and not at home.

A coagulation panel can be useful:

• ahead of a planned procedure where a clinic or dentist has asked for clotting values
• when bleeding symptoms have been going on for a while and you want to walk into a consultation with something concrete
• while monitoring known liver disease, since the liver makes the clotting factors
• when a family member has a diagnosed bleeding disorder and you want to see where your own values sit

Each value is shown next to the reference range of the laboratory that analysed your blood. That matters more here than it does for many other assays: the result depends on the reagent and the analyser used, so ranges differ from lab to lab. The same aPTT can land mid-range at one lab and just above the range at another.

A value outside the range is not a diagnosis. It means this measurement differs from what the lab sees in most people, and nothing more than that. Mild deviations in a single value are found regularly in people who have never had a bleed worth noticing.

Your results are online within a few working days. For each value you see your own measurement next to the lab reference range, with a plain-language explanation.

Every result includes a professional assessment from a BIG-registered doctor. If a value falls outside the range, discuss it with your GP, who can weigh it against your symptoms, your medication and your history and decide whether follow-up testing makes sense.