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Side Effect: Prolonged Clotting Time (increased aPTT and PT)

What is Prolonged Clotting Time (increased aPTT and PT)?

Prolonged or increased clotting time is a medical condition where the blood takes longer than normal to form a blood clot. The two common tests used to assess clotting time are activated partial thromboplastin time (aPTT) and prothrombin time (PT).

The process of blood clotting, also known as coagulation, is a complex process involving blood cells called platelets and proteins called clotting factors. When clotting factors are missing or damaged or when the body does not have enough platelets, or the platelets are not working correctly, it takes longer for your body to stop any bleeding resulting in an increased clotting time.

What does Prolonged Clotting Time (increased aPTT and PT) look like?

Clotting time tells us how long it takes for your blood to form a protective “patch” when you get a cut or injury. We typically measure clotting time using thr lab values call aPTT or PT.

If your clotting time is longer than usual, you might notice increased bleeding or bruising, especially if you have other risk factors such as a low platelet count or if you are taking medications that affect platelets, such as ibuprofen or aspirin.

Other than irregular lab values, you might notice the following:

Prolonged Clotting Time (increased aPTT and PT)

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Who gets Prolonged Clotting Time (increased aPTT and PT)?

Bleeding issues including prolonged clotting time can happen due to many reasons that are often not related to cancer. However, some types of cancer and their treatments can lead to bleeding problems or make existing bleeding problems worse.
Certain types of cancers such as hematologic malignancies like leukemia or lymphoma, or solid tumors with metastasis to the liver, lungs, or brain, have an increased risk of bleeding due to increases in clotting time.

If the liver is damaged to a large degree, it may not be able to produce the same amount of clotting factor as it had made in the past. This may lead to a prolongation in the aPTT and PT tests.

Medications used to treat blood clots are designed to prolong the aPTT or PT in order to allow your body time to break down unwanted clots. For this reason, these medications also carry a small risk of bruising and bleeding, and the benefits of preventing the blood clot from getting bigger must be weighed against the risk of bleeding.

How to prevent Prolonged Clotting Time (increased aPTT and PT)

Preventing a prolonged clotting time in patients with cancer involves careful monitoring of coagulation parameters and platelet counts, avoiding unnecessary invasive procedures, and administering appropriate blood products or antifibrinolytic agents as needed.

Maintaining a balanced diet rich in vitamins and minerals will help support healthy clotting. Additionally, staying hydrated can have a positive impact on blood viscosity and clotting.

How to treat Prolonged Clotting Time (increased aPTT and PT)

The treatment of prolonged clotting time in patients with cancer depends on the underlying cause. The most common treatment is the administration of appropriate blood products, such as fresh frozen plasma or cryoprecipitate. In certain cases, antifibrinolytic agents, such as tranexamic acid, may also be used.

When possible, it is best to treat the underlying cause.


1. Balboni, F., & Lippi, G. (2018). How can we deal with an unexpected preoperative prolongation of the activated partial thromboplastin time (APTT)? —a real world experience. Journal Of Laboratory And Precision Medicine, 3.

Created: March 10, 2024 Updated: March 11, 2024