COAGULATION PROFILE

✓ Medically ReviewedINVESTIGATIONID: MDBT0301🚨 TRIAGE: URGENTICD-10: R79.1

📖

Definition

CLINICAL DEFINITION

A coagulation profile is a panel of laboratory tests that assesses the integrated function of the coagulation cascade. It typically comprises the prothrombin time (PT), activated partial thromboplastin time (aPTT), and fibrinogen concentration, with the international normalised ratio (INR) derived from the PT. The panel screens for deficiencies or inhibitors of coagulation factors, monitors anticoagulant therapy, and evaluates synthetic liver function.

IN PLAIN ENGLISH

A coagulation profile is a group of blood tests that check how well your blood clots. It helps doctors find out why someone might bleed too easily or clot too much, and it is used to monitor medicines that affect clotting.

COMMON MISCONCEPTION / WHAT IT DOES NOT MEAN

A coagulation profile is NOT a comprehensive thrombophilia screen. It does not include specific assays for protein C, protein S, antithrombin, or genetic mutations, and a normal profile does not exclude all bleeding disorders (e.g., von Willebrand disease, platelet function defects).

🔤

Word Breakdown

coagul-

=from Latin 'coagulare' — to curdle, to cause to clot

-ation

=from Latin '-atio' — process or action

Literal Meaning: The process of causing a liquid to become a soft solid mass, applied to blood

🏷️

Abbreviations

PT=Prothrombin Time — measures the extrinsic and common coagulation pathways; prolonged in vitamin K deficiency, warfarin therapy, and liver disease

aPTT=Activated Partial Thromboplastin Time — measures the intrinsic and common pathways; prolonged in heparin therapy, haemophilia, and lupus anticoagulant

INR=International Normalised Ratio — standardised PT ratio used to monitor vitamin K antagonist therapy and assess liver synthetic function

TT=Thrombin Time — measures conversion of fibrinogen to fibrin; prolonged by heparin, direct thrombin inhibitors, and dysfibrinogenaemia

🔄

Synonyms & Variants

Coagulation Screen›Clotting Profile›Coagulogram›

🎯

Category-Specific Context

As an Investigation, the coagulation profile provides objective laboratory data about the coagulation system. It is not a diagnostic entity in itself; rather, it is a screening and monitoring tool used to generate hypotheses about underlying bleeding or thrombotic disorders. Results must be integrated with the patient's history, physical examination, platelet count, and, when indicated, specific factor assays or mixing studies.

🏥

Clinical Context & Usage

CLINICAL SETTINGS

Emergency DepartmentHaematology Outpatient ClinicIntensive Care UnitOperating TheatreGeneral Medicine WardAntenatal ClinicLiver Transplant Unit

USAGE & DOCUMENTATION NOTES

In clinical documentation, the profile is often recorded as 'Coagulation screen: PT 13 s, INR 1.0, aPTT 30 s, fibrinogen 3.0 g/L.' On ward rounds, clinicians refer to a 'prolonged PT' or 'isolated aPTT prolongation' and correlate with the bleeding history. Referral letters may state 'coagulation profile normal' or 'coagulopathy with INR 1.8' to communicate bleeding risk. When monitoring warfarin, only the INR is typically reported and trended.

🔬

Primary Causes & Pathophysiology

PATHOPHYSIOLOGY

The coagulation profile interrogates the coagulation cascade in vitro. The PT reagent contains tissue factor and phospholipid, activating the extrinsic pathway (factor VII) and the common pathway (factors X, V, II, and fibrinogen); prolongation suggests deficiency or inhibition of these factors. The aPTT reagent provides a contact activator and phospholipid, activating the intrinsic pathway (factors XII, XI, IX, VIII) and the common pathway; prolongation suggests deficiency or inhibition of intrinsic or common factors. Fibrinogen is measured directly (often by the Clauss method) and reflects the substrate for fibrin formation. The INR standardises PT results across thromboplastin reagents using the International Sensitivity Index, allowing comparison across laboratories. Abnormal results may reflect true factor deficiency, an inhibitor (e.g., heparin, lupus anticoagulant, a specific factor inhibitor), or pre-analytical variables.

PRIMARY CAUSES

Liver disease (reduced hepatic synthesis of coagulation factors)

The liver synthesises factors II, V, VII, IX, X, XI, and fibrinogen; hepatocellular dysfunction reduces their production, prolonging PT and aPTT, often with low fibrinogen in advanced disease.

Vitamin K deficiency (malnutrition, malabsorption, obstructive jaundice, prolonged antibiotics)

Vitamin K is required for γ-carboxylation of factors II, VII, IX, and X; deficiency functionally impairs these factors, typically prolonging PT first (short half-life of factor VII) and later aPTT.

Disseminated intravascular coagulation (DIC)

Widespread activation of coagulation consumes factors and fibrinogen and triggers fibrinolysis; the profile shows prolonged PT and aPTT, low fibrinogen, and elevated D-dimer.

Anticoagulant therapy (warfarin, heparin, direct oral anticoagulants)

Warfarin inhibits vitamin K–dependent factor synthesis (prolongs PT/INR); heparin potentiates antithrombin (prolongs aPTT); direct thrombin inhibitors prolong aPTT and TT; direct factor Xa inhibitors prolong PT.

Inherited coagulation factor deficiencies (haemophilia A/B, von Willebrand disease, rare factor deficiencies)

Absent or reduced factor VIII/IX (haemophilia) prolongs aPTT; factor VII deficiency prolongs PT; combined deficiencies affect both pathways; von Willebrand disease may variably prolong aPTT.

Massive transfusion or major haemorrhage

Dilution and consumption of coagulation factors and fibrinogen produce a coagulopathy with prolongation of PT and aPTT and low fibrinogen.

💊

Drug-Induced Causes

💊 Vitamin K antagonists (warfarin, acenocoumarol) ↗

Mechanism: Inhibit vitamin K epoxide reductase, reducing synthesis of functional factors II, VII, IX, and X; PT/INR is the primary monitoring test.

→ Hold warfarin if INR supratherapeutic; administer vitamin K (phytomenadione) for significant elevation or bleeding; urgent reversal with prothrombin complex concentrate if major bleeding.

💊 Unfractionated heparin ↗

Mechanism: Potentiates antithrombin-mediated inhibition of thrombin and factor Xa, prolonging aPTT (and TT at higher doses).

→ Stop heparin if bleeding; protamine sulfate can reverse unfractionated heparin; monitor aPTT or anti-Xa depending on protocol.

💊 Direct thrombin inhibitors (dabigatran, argatroban, bivalirudin) ↗

Mechanism: Directly inhibit thrombin, prolonging aPTT and thrombin time (TT); PT may also be affected.

→ Discontinue agent; specific reversal with idarucizumab for dabigatran in life-threatening bleeding; supportive measures for others.

💊 Direct factor Xa inhibitors (rivaroxaban, apixaban, edoxaban) ↗

Mechanism: Directly inhibit factor Xa, prolonging PT more than aPTT; aPTT may be normal or mildly prolonged.

→ Discontinue agent; andexanet alfa (where available) for life-threatening bleeding; otherwise supportive care and timing of last dose guide management.

🌍

Epidemiology

Prevalence:Coagulation profiles are among the most commonly ordered laboratory panels in hospitalised patients; abnormalities are frequent in critically ill, liver disease, and anticoagulated populations. Precise general-population prevalence of abnormal results is not well defined and varies by assay and threshold.

Age Group:All age groups; interpretation differs in neonates (physiologically lower vitamin K–dependent factors and longer PT/aPTT reference ranges) and older adults (higher prevalence of liver disease, malignancy, and anticoagulant use).

Geographic Distribution:Globally applicable; reference ranges vary by laboratory and reagent, and access to specific factor assays or mixing studies differs by region. No consistent geographic predilection.

Red Flags & Triage ★

TRIAGE LEVEL

🚨 URGENT

DO NOT MISS — LIFE-THREATENING PRESENTATIONS

Prolonged PT and aPTT with low fibrinogen and thrombocytopenia in a bleeding patient — consider disseminated intravascular coagulation and evaluate urgently with D-dimer and fibrinogen.
Isolated aPTT prolongation in a patient with bleeding — consider haemophilia or a specific factor inhibitor; a mixing study is required before attributing to lupus anticoagulant (which typically causes thrombosis, not bleeding).

URGENT EVALUATION TRIGGERS

Active bleeding with prolonged PT/INR or aPTT beyond the upper limit of normal
Suspected disseminated intravascular coagulation (bleeding plus prolonged PT/aPTT and low fibrinogen)
INR >5.0 or aPTT >100 s, even without bleeding, in a patient at high risk of haemorrhage
New neurological deficit or severe headache in a patient with abnormal coagulation — consider intracranial haemorrhage

Contraindications & Precautions

CONTRAINDICATIONS

No absolute contraindications to performing a coagulation profile; however
testing may be deferred in acute severe infection or inflammatory states if the result is unlikely to alter immediate management and local policy advises postponement.

SPECIAL PRECAUTIONS

Avoid testing on haemolysed
clotted
or underfilled citrate samples
as these produce spurious results
particularly aPTT prolongation.
Document anticoagulant use (including timing of last dose) and communicate it to the laboratory
as heparin
warfarin
and direct oral anticoagulants affect results.
Avoid drawing blood from a line infusing heparin; use a separate venepuncture where possible.
Repeat abnormal results before acting on them unless the patient is actively bleeding
because coagulation tests are prone to pre-analytical error.
A normal coagulation profile does not exclude a bleeding disorder (e.g.
von Willebrand disease
platelet function defect); pursue specific testing if clinical suspicion persists.

📏

Reference Ranges

NORMAL RANGETypical adult reference intervals vary by laboratory; representative ranges: PT 11–15 s; INR 0.8–1.2 (untreated); aPTT 25–38 s; fibrinogen 1.5–4.0 g/L. Neonatal ranges differ.

CRITICAL (PANIC) VALUEINR >5.0 or aPTT >100 s with active bleeding; fibrinogen <1.0 g/L in a bleeding patient — warrants urgent clinical review and consideration of factor replacement.

UNIT OF MEASUREMENTPT and aPTT: seconds (s); INR: dimensionless ratio; fibrinogen: grams per litre (g/L).

🔀

Confused With (LASA & DDx) ★

LEXICAL (LASA) — SIMILAR NAMES

Coagulation Factors

Coagulation profile is the panel of tests; coagulation factors are the individual proteins measured or inferred by the panel. Confusing the panel with the factors can lead to incorrect ordering of specific assays.

CLINICAL DIFFERENTIAL DIAGNOSES (DDx)

Platelet function disorder

Key Distinguishing Feature: Coagulation profile is typically normal; diagnosis requires platelet function testing (e.g., platelet aggregometry) and a compatible bleeding history.

Von Willebrand disease

Key Distinguishing Feature: Coagulation profile may show isolated aPTT prolongation or be normal; specific von Willebrand factor antigen and activity assays are required.

Factor XIII deficiency

Key Distinguishing Feature: PT, aPTT, and fibrinogen are normal; clot solubility test or specific factor XIII assay is required.

💎

Clinical Pearls

💎

A prolonged aPTT that corrects on a 1:1 mixing study with normal plasma suggests a factor deficiency; failure to correct suggests an inhibitor (e.g., heparin, lupus anticoagulant, or a specific factor inhibitor).

💎

The PT is more sensitive than the aPTT to early vitamin K deficiency or liver synthetic dysfunction because factor VII has the shortest half-life.

💎

A normal coagulation profile does not exclude clinically significant bleeding disorders such as von Willebrand disease, platelet function defects, or factor XIII deficiency.

💎

When interpreting an abnormal coagulation profile, always consider pre-analytical variables (sample haemolysis, underfilling, delay in processing, heparin contamination) before diagnosing a coagulopathy.

📝

Example Usage & SOAP

CLINICAL SENTENCE

""Coagulation profile on admission: PT 18 s, INR 1.6, aPTT 42 s, fibrinogen 1.1 g/L, consistent with a consumptive coagulopathy; D-dimer elevated.""

IN A SOAP NOTE

S: 58-year-old male with cirrhosis presenting with melaena and hypotension. O: BP 88/52 mmHg, HR 112/min; Hb 7.8 g/dL; coagulation profile: PT 22 s, INR 1.9, aPTT 48 s, fibrinogen 0.9 g/L. A: Upper GI bleed with coagulopathy secondary to cirrhosis. P: Resuscitate with blood products; transfuse fresh frozen plasma and fibrinogen concentrate; urgent endoscopy; monitor coagulation profile after each intervention.

DIFFERENTIAL DIAGNOSIS CONTEXT

Differential for prolonged aPTT with normal PT: (1) heparin contamination or therapy — check thrombin time and anti-Xa; (2) haemophilia A or B — mixing study corrects, specific factor VIII/IX assay; (3) von Willebrand disease — aPTT may be mildly prolonged, check vWF antigen/activity; (4) lupus anticoagulant — mixing study may not correct, but typically causes thrombosis not bleeding; (5) factor XII deficiency — not a bleeding disorder. The clinical bleeding history and mixing study guide the sequence.

📊

Classifications & Scoring

SCORING TOOL

ISTH DIC Score

International Society on Thrombosis and Haemostasis overt DIC scoring system using platelet count, elevated fibrin-related marker, prolonged PT, and fibrinogen. A score of ≥5 is compatible with overt DIC; requires underlying condition known to be associated with DIC.

📚

References & Coding

ICD-10 DIAGNOSTIC CODE

R79.1

LITERATURE CITATIONS & GUIDELINES

[1]Gulati GL, Adcock DM, Rhoades R. Interpretation of Results of Routine and Special Coagulation Tests: A Practical Guide. Oxford University Press. 2025.

[2]British Society for Haematology. Guidelines on the laboratory aspects of assays used in haemostasis and thrombosis. BSH. (Accessed 2026).

[3]NICE NG45. Routine preoperative tests for elective surgery. 2016 (updated).

[4]Prolonged coagulation times — York and Scarborough Teaching Hospitals NHS Foundation Trust pathway. 2025.

MEDICAL DISCLAIMER — This content is intended for educational purposes and qualified healthcare professionals only. Always refer to current clinical diagnostic criteria, institutional protocols, and official guidelines. Medobo is not responsible for clinical decisions made based on this content.