[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [General pathology](https://durgical.com/en/general-pathology/) › [Red cells and bleeding disorders](https://durgical.com/en/general-pathology/areas/red-cells/) › Acquired coagulation factor disorders

# Acquired coagulation factor disorders

- Mechanism

Most clotting factor problems are acquired: too little vitamin K, a failing liver, antibodies against a factor, or venom that eats fibrinogen.

Updated Nov 12, 2026

## Key points

- Vitamin K-dependent factors: II, VII, IX, X and proteins C and S; factor VII has the shortest half-life, so PT prolongs first.
- Newborns: low vitamin K stores and sterile gut; prophylactic vitamin K at birth prevents vitamin K deficiency bleeding.
- Liver disease: low factors, low fibrinogen, thrombocytopenia from hypersplenism and altered fibrinolysis.
- Factor inhibitors: prolonged PTT that does not correct on mixing with normal plasma.
- Bothrops envenomation: thrombin-like enzymes consume fibrinogen, causing incoagulable blood, local necrosis and bleeding.

## What it is

Acquired coagulation defects usually affect several factors at once. Vitamin K is needed to γ-carboxylate factors II, VII, IX and X and proteins C and S; deficiency follows poor intake, fat malabsorption, antibiotics that kill gut flora, newborn status or vitamin K antagonist drugs and rodenticides. The liver makes most clotting factors, so severe liver disease causes complex bleeding. Autoantibodies against a single factor (acquired haemophilia, usually against factor VIII) are rare but dangerous. Venom of Bothrops snakes, the commonest venomous bites in Colombia, activates and consumes fibrinogen and other factors.

## Step by step

- Vitamin K is absent or blocked (warfarin, superwarfarin rodenticides) or the liver cannot synthesize factors.
- Factors are made but not γ-carboxylated, so they cannot bind calcium and phospholipid surfaces.
- PT prolongs first (factor VII), then PTT as other factors fall.
- Alternatively, venoms or DIC consume fibrinogen and factors faster than the liver replaces them.
- Bleeding appears from mucosae, wounds, gut and brain.

## Acquired coagulation defects

| Cause | Mechanism | Typical tests | Context |
| --- | --- | --- | --- |
| [Vitamin K deficiency or antagonists](https://durgical.com/en/conditions/vitamin-k-deficiency-bleeding-of-the-newborn/) | No γ-carboxylation of II, VII, IX, X | Long PT, then long PTT; corrects with vitamin K | Newborns, malabsorption, antibiotics, warfarin, rodenticides |
| [Liver disease](https://durgical.com/en/conditions/cirrhosis/) | Reduced synthesis of most factors | Long PT and PTT, low fibrinogen, low platelets | Cirrhosis, acute liver failure |
| [DIC](https://durgical.com/en/conditions/disseminated-intravascular-coagulation/) | Consumption of factors and platelets | Long PT and PTT, low fibrinogen, high D-dimer | Sepsis, obstetric emergencies, cancer |
| Acquired factor inhibitor | Autoantibody, usually against factor VIII | Long PTT not corrected by mixing | Older adults, postpartum, autoimmune disease |
| [Bothrops snakebite](https://durgical.com/en/conditions/snakebite-envenomation/) | Venom enzymes consume fibrinogen | Incoagulable blood, very low fibrinogen | Rural Colombia and Latin America |

## Clinical notes

- Vitamin K deficiency bleeding of the newborn can be early, classic or late (intracranial); prophylaxis at birth prevents it.
- Antivenom, not plasma alone, reverses Bothrops coagulopathy.

## Memory aid

Two, seven, nine, ten, C and S need vitamin K; seven leaves first, so the PT tells first.

## Test yourself

Think of the answer, then tap the question to see it.

## Which factors depend on vitamin K?

Factors II, VII, IX and X, and the anticoagulant proteins C and S.

## Why is the PT the first test to prolong in vitamin K deficiency?

Factor VII has the shortest half-life, and the PT is most sensitive to it.

## How does Bothrops venom cause bleeding?

Its enzymes activate and consume fibrinogen and other factors, leaving the blood unable to clot.

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## Elsewhere in DurgiPedia

- [Vitamin K (phylloquinone)](https://durgical.com/en/biochemistry/molecules/vitamin-k/)
- [Vitamin K epoxide reductase (VKORC1)](https://durgical.com/en/biochemistry/enzymes/vitamin-k-epoxide-reductase/)
- [The coagulation cascade](https://durgical.com/en/physiology/the-coagulation-cascade/)
- [Coagulation tests: PT/INR, aPTT and platelets](https://durgical.com/en/physiology/coagulation-tests-pt-inr-aptt-and-platelets/)

## Connections

## Related 4

- [Disseminated intravascular coagulation: how consumption causes both clots and bleeding](https://durgical.com/en/general-pathology/disseminated-intravascular-coagulation-how-consumption-causes-both-clots-and-ble/)
- [Liver failure: acute, chronic and acute-on-chronic](https://durgical.com/en/general-pathology/liver-failure-acute-chronic-and-acute-on-chronic/)
- [Bleeding disorders: overview](https://durgical.com/en/general-pathology/bleeding-disorders-overview/)
- [Vitamin deficiencies: what each one does to tissue](https://durgical.com/en/general-pathology/vitamin-deficiencies-what-each-one-does-to-tissue/)

## Related conditions 7

- [Vitamin K deficiency bleeding of the newborn](https://durgical.com/en/conditions/vitamin-k-deficiency-bleeding-of-the-newborn/)
- [Anticoagulant poisoning (warfarin and superwarfarins)](https://durgical.com/en/conditions/anticoagulant-poisoning/)
- [Cirrhosis](https://durgical.com/en/conditions/cirrhosis/)
- [Acute liver failure](https://durgical.com/en/conditions/acute-liver-failure/)
- [Snakebite envenomation (Bothrops, Lachesis, Crotalus)](https://durgical.com/en/conditions/snakebite-envenomation/)
- [Disseminated intravascular coagulation](https://durgical.com/en/conditions/disseminated-intravascular-coagulation/)
- [Coeliac disease](https://durgical.com/en/conditions/coeliac-disease/)

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Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [Vitamin K deficiency bleeding of the newborn: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/007320.htm) (MedlinePlus, US National Library of Medicine, 2026); [Vitamin K: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/002407.htm) (MedlinePlus, US National Library of Medicine, 2026).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/general-pathology/acquired-coagulation-factor-disorders/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/general-pathology/acquired-coagulation-factor-disorders/