Factor IX

The liver produces a protein called factor IX (F-IX), vital in the natural coagulation process. A triggering agent (factor IX A) activates FI-X upon injury and damage to the blood vessels. The activated variant then enables blood vessels to clot, preventing excessive bleeding.

A factor IX deficiency usually leads to haemophilia B, a bleeding disorder in which blood fails to clot naturally. Some other symptoms of the condition include the following:

• Unusual nosebleeds
• Excessive bleeding from minor cuts or bleeding from a previous wound
• Oral bleeding
• Blood in stool or urine
• Bruises for no apparent reason

In terms of severity, haemophilia B can be life-threatening if not managed or treated consistently. Even a minor impact on the head could lead to internal bleeding in the brain, which can be fatal. In such cases, internal cerebral bleeding will manifest as the symptoms listed below:

• Sudden headache
• Pain or stiffness in the neck 
• Drowsiness 
• Impairment in motor functions

A factor IX deficiency often stems from associated genetic history and predominantly affects males. Females who inherit one defective Factor IX gene do not show visible symptoms and become carriers. There is a 50% chance of their male babies developing the condition in such cases.

There are some instances of acquired factor IX deficiency (stemming from external sources instead of genetics). Some factors that cause the same include the following:

• Vitamin K deficiency
• Liver diseases
• Anticoagulant medications such as clotting inhibitors or Warfarin therapy (rarely)

A factor IX test (F-IX test) is part of a more extensive screening test for bleeding disorders. In a clinical context, a deficiency in the protein leads to a diagnosis of haemophilia B. Test results also help assess the general levels of the protein present in an individual.

The F-IX test is performed in the Laboratory ACL TOP with the help of the activated partial thromboplastin time (APTT) method.

Testers combine the patient specimen with factor IX-deficient plasma. The compound then incubates for an allotted period alongside a reagent. Subsequently, calcium is added to the mix to activate the coagulation process.

Testers observe the clotting time through an optical device at a 671 nm wavelength. An assessment of the clotting time establishes F-IX concentrations in the patient specimen.

Infants under or equal to 6 months of age usually display decreased F-IX levels (20 unit/dL or less). The concentration levels increase as they age. In adults, normal levels range from 50-150 units/dL.

F-IX test results below 50 units/dL indicate haemophilia B, with severity levels increasing as the concentration drops. Conversely, elevated protein levels increase the chances of an individual developing deep vein thrombosis (blood clots in the veins).

Apollo 24|7 offers a factor IX test that assesses the associated protein levels to diagnose related disorders or deficiencies. The test result can also provide insight into the following:

• The impact of liver diseases on the production of F-IX and, thus, haemostasis (body’s natural response to stop bleeding)
• Additional implications behind a prolonged APTT (clotting time)
• Existence of other blood-related disorders such as thrombosis
   

Frequently asked questions

Why does haemophilia B primarily affect males?

Haemophilia B typically affects males due to the biological differences between the two genders. Factor IX is present in the X-chromosome, and a deficiency usually means it's absent from the chromosomal makeup. Males have X and Y chromosomes, while females have two X-chromosomes. So, for women, if the factor IX protein is missing in one X-chromosome, the other makes up for it. For males, that becomes impossible due to the presence of only one X-chromosome. This is why haemophilia affects males more than females. However, it's essential to note that females with two defective factor IX genes can also develop the condition.

Is haemophilia B curable?

Currently, there is no cure for haemophilia B. The condition is chronic, and treatment includes injections or infusions of the factor IX protein into affected individuals. The infusion amount varies depending on the severity of the disease.

Can haemophilia go undiagnosed?

The condition can go undiagnosed until late into adulthood. In several cases, people with mild haemophilia are not diagnosed until they require surgery or suffer from an injury. Mild variants of the condition can also result in a prolonged interim period between bleeding episodes.

What other tests can supplement the factor IX test?

Most medical experts recommend taking the following tests to supplement a factor IX test: Activated Partial Thromboplastin Time (APTT) test & Prothrombin Time (PT) Test Blood Count Test  Fibrinogen Test Urine and Stool analysis All the above-listed tests can help in the screening process for a bleeding disorder.

Are there any preparatory steps for taking the test?

There are no additional requirements for taking the factor IX test. However, in case of any family history of bleeding disorders, it's essential to inform the test technician or the doctor before taking the test. Failure to do so could result in potential complications.

What can cause the test sample to be rejected?

Test samples can be declared invalid or rejected in the following circumstances: Gross haemolysis (Red blood cells breaking down during sample collection) Gross lipemia (Presence of high concentrations of unsaturated fat in the blood sample) Gross icterus (if the test subject has jaundice)