V Deficiency Overview
Factor V deficiency is also known as Owren’s disease or
parahemophilia. It’s a very rare blood clotting disorder that results in slow
or prolonged blood clotting after an injury or surgery. Factor V, or
proaccelerin, is a protein made in your liver that helps convert prothrombin
into thrombin. This is an important step in the blood clotting process. Your
blood clots may be too weak to stop you from bleeding if you don’t have enough
factor V or if it doesn’t work properly.
Factor V deficiency may occur at the same time as factor
VIII deficiency, producing more severe blood clotting problems. A combination
of factor V and factor VIII deficiencies is considered to be a separate
What Role Does Factor V Play in Normal Blood Clotting?
Factor V is one of about 13 clotting factors responsible for
normal blood coagulation. Blood clotting occurs in stages:
- When your blood vessel is cut, it immediately
constricts to slow blood loss. This is
called vasoconstriction. It then releases cells into your bloodstream that
tell the blood clotting factors to start the coagulation process.
- Blood platelets collect at the site of the wound
and begin sticking to the wound and to each other. This forms a soft platelet
plug in your wound. This stage is called primary hemostasis.
- Once the platelets form a temporary plug, a
complex chain reaction takes place among multiple blood clotting factors.
Factor V appears about halfway through this chain of reactions and converts
prothrombin into thrombin.
- Thrombin triggers fibrinogen to produce fibrin, which
is the material that makes up the final blood clot. Fibrin is a stringy
protein that wraps itself in and around the temporary soft clot, which makes
the clot harder and more resistant. This new clot seals the broken blood vessel
and creates a protective covering for tissue regeneration. This stage is called
- After a few days, the fibrin clot
starts to shrink, pulling the edges of the wound together to allow the damaged
tissue to rebuild. As the underlying tissue is rebuilt, the fibrin clot
Secondary hemostasis doesn’t occur properly if you have
factor V deficiency. This results in prolonged bleeding.
Causes Factor V Deficiency?
Factor V deficiency may be inherited or acquired after
birth. Hereditary factor V deficiency is extremely rare. It’s caused by a
recessive gene, which means that you have to inherit the gene from both of your
parents in order to show symptoms. There are only 105 documented cases of
inherited factor V deficiency in the world.
Acquired factor V deficiency may be caused by certain medications,
underlying medical conditions, or an autoimmune reaction. Conditions that might
affect factor V include:
- disseminated intravascular coagulation (DIC),
which is a condition that causes small blood clots and excessive bleeding due
to overactive clotting proteins
- liver diseases, such as cirrhosis of the liver
- secondary fibrinolysis, which occurs when fibrin
clots tend to break down
- autoimmune diseases, such as lupus
- spontaneous autoimmune reactions after surgery
- certain types of cancer
Are the Symptoms of Factor V Deficiency?
The symptoms of factor V deficiency are generally very mild.
Factor V levels can be as low as 10-20 percent of normal and your blood will
still clot, although a bit more slowly.
In cases of severe factor V deficiency, the symptoms may
- abnormal bleeding after giving birth, having
surgery, or being injured
- abnormal bleeding under the skin
- umbilical cord bleeding at birth
- nose bleeds
- bleeding gums
- easy bruising
- heavy or prolonged menstrual periods
Is Factor V Deficiency Diagnosed?
Many people who have this condition are diagnosed when doctors
run blood coagulation tests before surgery. Common lab tests for factor V include
assays measure the performance of specific clotting factors to
identify missing or poorly performing factors.
- Factor V
assay measures how much factor V you have and how well it works.
time (PT) measures clotting time affected by factors I, II, V, VII,
prothrombin time (PTT) measures clotting time affected by factors
VIII, IX, XI, XII and von Willebrand factors.
tests determine if your immune system is suppressing your blood
doctor will likely order other tests to identify any underlying
conditions resulting in factor V deficiency.
Is Factor V Deficiency Treated?
Since factor V deficiency is generally mild, treatment is
mostly precautionary. Your doctor may recommend you use desmopressin (DDAVP)
before surgery or dental procedures. DDAVP is a nasal spray that temporarily
boosts your factor levels. In the event of a severe bleeding episode, you may
be given infusions of fresh frozen plasma (FFP) and blood platelets to replace
your missing blood clotting factor.
Is the Outlook for People with Factor V Deficiency?
Factor V deficiency is relatively manageable compared to
other blood clotting disorders. Most people who have this condition need treatment
only after surgery or a very serious injury. People who have this condition
usually live normal lives and only bleed a little bit longer than people who
have blood that coagulates normally.