Complete coagulation panel: eight values from one blood draw

A four-value screen tells you whether the clotting chain is slowed and at which end. This panel starts where that screen stops. It adds four measurements that each look at the same chain from a different angle, so a single draw leaves you with more than just a direction to search in.

Prothrombin time (PT) measures the same laboratory reaction as the INR, but reports it in seconds rather than as a ratio. A laboratory report puts the two side by side, which is why you see both here. Thrombin time isolates the final step of the chain: the conversion of fibrinogen into fibrin. D-dimer measures something different again, namely the fragments left behind when the body breaks a clot down. And antithrombin III is the body's own brake on clotting, the protein that keeps the chain from running on further than it should.

This tier is for people who would rather get all eight values out of one appointment than come back for a second. If you only want to know whether the basics are in order, the four-value coagulation panel covers that.

This extended coagulation panel may suit:

• people for whom bruising or prolonged bleeding has become more frequent than it used to be
• people whose doctor asked for clotting values and who would rather not wait for a referral
• people in whose family a bleeding or clotting disorder has been diagnosed
• people with liver disease, since the liver makes the proteins this panel measures
• people with clots in the family who want to see where their values sit before starting oestrogen-containing contraception or a pregnancy
• people already being investigated who want concrete numbers to bring into a consultation

There is one group this panel is not for, and that exclusion holds as firmly as the rest of the list. Do not order it within roughly three months of a clot, or while you are taking anticoagulants. Antithrombin III is consumed while a clot forms and is lowered by heparin, and D-dimer stays raised throughout that period. The result would not be readable. And if you take anticoagulants and want your INR checked so your dose can be adjusted, that monitoring stays with your anticoagulation clinic.

You get eight values, spread across the whole chain:

• INR: the standardised result of the clotting route that starts outside the vessel, which is what makes labs comparable with each other.
• PT (prothrombin time): the same reaction, reported in seconds instead of as a ratio.
• aPTT: how long the route that starts inside the vessel takes to complete.
• Thrombin time (TT): the final step measured on its own, fibrinogen turning into fibrin.
• Fibrinogen: how much raw material is available for the conversion the thrombin time measures.
• Platelets: how many platelets are available to make that first plug with.
• D-dimer: the fragments released when a clot is broken down again.
• Antithrombin III (activity): how well the natural brake on clotting is working.

Seeing both INR and PT on that list is not duplication. They come from one and the same laboratory reaction: the lab times the clot in seconds and converts that figure into the INR. A laboratory report gives the two together as a matter of routine, and so do we.

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

The four screening values show whether the chain is slowed and at which end. The four additions fill in points the screen leaves open.

A normal D-dimer makes it unlikely that a clot formed recently. Ruling out is what the assay is good at, though a normal result lowers the likelihood rather than excluding a clot outright; how much weight it carries depends on the clinical suspicion. In the other direction it works far less well. A raised D-dimer has many possible causes and means little by itself; how likely a clot actually is remains a clinical judgement, made by a doctor from your symptoms and your situation rather than from the number.

A low antithrombin III can be inherited, but far more often it is acquired: through liver disease, protein lost through the kidneys, a recent clot, or treatment with heparin. One low reading is therefore not a conclusion. What it means depends on what else is going on, which is exactly what a doctor weighs alongside it.

No single value in this panel establishes a clotting disorder on its own. What the panel does is sharpen the question and give a doctor a starting point for whatever may be needed next.

The sample is a venous draw, taken at one of our 700+ certified sample points across the Netherlands. Which location, and which slot, is yours to choose once the order is in.

All eight values come from that same draw, so the four extra measurements do not mean a second visit.

Coagulation assays are collected into a citrate tube that has to be filled exactly to the mark and reach the lab quickly, or the results drift. That is why trained staff take the sample at a certified location, rather than you taking it at home.

This extended panel can be useful:

• when an earlier coagulation screen showed something and you want more values before a follow-up consultation
• when clots run in your family and you want to see where your values sit before starting oestrogen-containing contraception or a pregnancy
• ahead of a planned procedure where a clinic or dentist has asked for a wider set of clotting values
• while monitoring known liver disease, since the liver makes both the clotting factors and antithrombin III
• but not within roughly three months of a clot, and not while you are on anticoagulants: wait until treatment is far enough behind you, because until then the values cannot be read

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

D-dimer carries one extra caveat. The value climbs with age and rises with pregnancy, infection, recent surgery, inflammation and cancer. In someone with no symptoms, a raised D-dimer is therefore usually traceable to one of those, and not to a clot.

A value outside the range is not a diagnosis. It means this measurement differs from what the lab sees in most people. Mild deviations in a single value are found regularly in people who have never had a bleed or a clot.

Your results are online within a few working days, with your own measurement shown next to the lab reference range for each value and a plain-language explanation. Every result includes a professional assessment from a BIG-registered doctor.

If all eight values sit inside the range, that is a quiet baseline for those eight measurements. Inherited clotting variants such as factor V Leiden are not among them, so do not let a decision about oestrogen-containing contraception or a pregnancy rest on this result alone; take it to your GP first. The FAQ below sets out what a thrombophilia workup adds. If antithrombin III is abnormal or D-dimer is raised, book an appointment with your GP rather than repeating the measurement yourself. Your GP can weigh the values against your symptoms, your medication and your history, and decide whether follow-up testing makes sense and which.