Clots in veins are the most common type with thrombophilia - this is called a 'venous thrombosis'. Possible symptoms are:
- Pain
and swelling in a leg. This occurs if you have a blood clot in a large
vein in a leg. This is commonly known as a 'deep vein thrombosis' or
'DVT'.
- The clot may travel to the heart and on into a lung, causing a
'pulmonary embolus' or 'PE'. Possible symptoms are chest pain, pain on
deep breathing, shortness of breath or rarely, collapse.
- Some types of thrombophilia can cause clots in unusual sites, such
as the brain, gut or liver. This can cause symptoms in the head or the
abdomen (tummy). Clots in liver veins are called 'Budd-Chiari syndrome'.
See separate leaflets 'Deep Vein Thrombosis (DVT)' and 'Pulmonary Embolism'.
Clots
in arteries can occur with some types of thrombophilia. Clots in
arteries can cause a stroke, a heart attack or problems with the
placenta during pregnancy. So the possible symptoms of artery clots due
to thrombophilia are:
- Having a stroke at a relatively young age
- Repeated miscarriages
- Pregnancy problems: pre-eclampsia, reduced fetal growth or rarely fetal death
- A heart attack
(But note that all of these can be due to causes other than thrombophilia.)
How is thrombophilia diagnosed?
Thrombophilia
may be suspected if you have a family history of blood clots at a young
age (under 45 years), or if you develop a blood clot which would not be
expected, given your age and general health.
What are the tests for thrombophilia?
Thrombophilia
is diagnosed by blood tests. A sample of blood is taken, and a number
of different tests will be done on it, to check different parts of the
clotting process.
Usually, the tests are done in two stages. The
first test is a ‘thrombophilia screen’ which is some basic clotting
tests. If the results of this suggest that thrombophilia is possible,
then another blood sample will be taken for more detailed tests. You
may be referred to a haematologist (a doctor specialising in blood
conditions). The doctor will usually ask about your history and family
history, which will help with interpreting the test results.
Can all thrombophilias be diagnosed on tests?
It
is likely that there are some kinds of thrombophilia which we cannot
yet identify or test for. This is because there are some patients or
families who get more blood clots than would normally be expected, yet
test negative on the thrombophilia tests. In this situation, you might
be advised to have treatment as for thrombophilia, even if you do not
have a definite diagnosis.
Who should be tested for thrombophilia?
Current guidelines suggest that thrombophilia testing should be considered in the following situations:
- Venous thrombosis or pulmonary embolus occurring under age of 45 years.
- Repeated episodes of venous thrombosis or pulmonary embolus or thrombophlebitis (inflamed veins).
- Venous thrombosis in an unusual site (eg abdomen or brain).
- Unexplained blood clots in newborn babies.
- Skin necrosis (patches of skin loss due to clots in the skin).
- A blood clot in an artery occurring under the age of 40 years.
- Relatives of patients with thrombophilia.
- Patients with clear family history of venous thrombosis.
- Certain blood test results: an unexplained 'prolonged activated
partial thromboplastin time' (an abnormal result on a certain type of
blood clotting test).
- Some patients with other medical conditions: recurrent miscarriage
or fetal death, idiopathic thrombocytopenic purpura (a condition
affecting blood platelets), or systemic lupus erythematosus ('lupus') -
because these can sometimes be linked to thrombophilia.
What is the treatment for thrombophilia?
The
first step is for you and your doctor to consider how much risk there
is of you getting an unwanted clot. This risk depends on a combination
of things, such as:
- What type of thrombophilia you have.
- Your age, weight, lifestyle and other medical conditions.
- Whether you are pregnant or have recently given birth.
- Whether you have already had a blood clot.
- Your family history - whether close relatives have had a blood clot.
This information will help your doctor to assess how much risk
you have of getting a clot, and what type of clot could occur. Then you
and your doctor can discuss the pros and cons of taking treatment, and
if needed, what type of treatment to take.
Possible treatments for thrombophilia are:
Low dose aspirin
This inhibits the action of
platelets, so can prevent clots. It may also help prevent miscarriage
or pregnancy problems, in some types of thrombophilia.
Anticoagulant treatment
Anticoagulant
medication slows down the clotting process. It is commonly used to
prevent or treat venous thrombosis and pulmonary embolism. In
thrombophilia, anticoagulant medication may be advised if:
- You have had a clot, to prevent another one.
- You have not had a clot, but have a very high risk of getting one.
- You have a temporary situation that puts you at high risk of a clot
- this may be the case if you are pregnant, within 6 weeks after
childbirth, or are immobile for a long period.
There are two types of anticoagulant: heparin and warfarin.
They work by slowing down the clotting process in the blood. Heparin is
taken as an injection once or twice daily. Warfarin is taken as a
tablet once daily.
With warfarin treatment, the dose has to be
adjusted on an individual basis. You will need a blood test which
checks the clotting speed, and then the dose is adjusted according to
the result. This can be done in an outpatient clinic, or sometimes by
your GP. Heparin doses may need to be adjusted in a similar way, or may
be taken as a fixed dose, depending on the type of heparin and on the
dose that is prescribed.
Treatment in pregnancy
If you are pregnant
or planning a pregnancy, discuss this your doctor, and tell your
midwife and obstetrician about the thrombophilia. Treatment for
thrombophilia may be different in pregnancy because:
- Some
women with certain types of thrombophilia are advised to take low-dose
aspirin while pregnant, to help prevent miscarriage or pregnancy
problems.
- The pregnancy itself increases the risk of a venous thrombosis -
this applies to the whole pregnancy and especially to the 6 weeks after
childbirth. So you may be advised to start anticoagulant treatment
while pregnant or after childbirth. This will depend on the type of
thrombophilia and your medical history.
- If you were taking warfarin, you will normally be advised to change
to heparin instead. This is because heparin is safer for the unborn
baby (there is a significant chance that warfarin could cause fetal
abnormalities). Both heparin and warfarin are safe for breastfeeding.
Prevention of venous thrombosis (DVT)
Certain
situations can put you at 'high risk' of venous thrombosis temporarily,
and in these situations you may be advised to take extra treatment for
a while. Examples are pregnancy and after childbirth, severe illness,
major surgery, or anything which immobilises you, such as travel or an
operation. Special stockings such as flight socks or compression
stockings may also be advised to help prevent a DVT.
General advice for people with thrombophilia
- If you are having any treatment or surgery, tell your doctor/nurse/pharmacist about the thrombophilia.
- Be aware of the warning symptoms of blood clots - get medical help immediately if you suspect one (see above for symptoms).
- Avoid dehydration by drinking adequate amounts of fluid - dehydration can contribute to blood clots.
- Keep active, and avoid being immobile for long periods - immobility helps cause venous thrombosis.
- Caution with medication: some medications increase the risk of
blood clots. For example, the combined oral contraceptive pill or patch
and hormone replacement therapy. You may be advised to avoid certain
medications, or to change to one which does not affect clotting.
- Keep to a healthy weight - being overweight increases the risk of a venous thrombosis.
- To keep blood vessels healthy (arteries in particular), do not
smoke. This is important if you have thrombophilia of a type that can
cause artery clots, as smoking promotes clots in arteries.
- Eat a balanced diet, including fresh fruit and vegetables, to help keep blood vessels healthy.
What are the complications of thrombophilia - and what is the outlook?
Often
there are no complications. Many forms of thrombophilia are mild in any
case, so that many people with thrombophilia have no problems from
their condition. Also, treatment can successfully prevent complications
in many cases.
If blood clots do occur there may be serious
complications. A pulmonary embolus, stroke, heart attack or a clot in
the brain or abdomen may all cause severe illness, or if the clot is
large enough they may be fatal. Early treatment can be life-saving and
reduces complications. So it is important to be aware of symptoms and
get treatment immediately if you suspect any kind of blood clot.
As
mentioned above, some types (not all) of thrombophilia may increase the
chance of problems in pregnancy. Your doctor can advise - it will
depend on the type of thrombophilia and also varies between
individuals. However, many women with thrombophilia have successful
pregnancies.
There may also be complications due to treatment.
Aspirin, heparin and warfarin can have side-effects, mainly unwanted
bleeding, such as internal bleeding from the stomach lining. For this
reason, it is important for you and your doctor to weigh up the pros
and cons of taking treatment, taking into account your individual
situation and preferences.
Testing relatives
If you or your family have
an inherited (genetic) form of thrombophilia, you may be asked to
consider tests for yourself or your close relatives, to see if you or
others in the family have the same condition. In most cases, tests are
not required for children, because children don't usually get blood
clots. So the child can normally wait until their teenage years before
considering thrombophilia tests.
What are the different types of thrombophilia?
This section explains the more common types of thrombophilia, although it does not cover every condition.
Inherited thrombophilias
Factor V Leiden
This is pronounced “factor 5
lyden”. It is fairly common in people of European origin, and about 1
in 20 Europeans have the factor V Leiden gene. This gene affects the
factor V part of the clotting cascade, making the clotting process go
on longer. It increases the risk of venous thrombosis by about eight
times - that is still a relatively low risk, so most people with factor
V Leiden do not develop clots. Some people inherit two factor V Leiden
genes - one gene from each parent (known as ‘homozygous Factor V
Leiden‘). This is less common, but makes the risk of venous thrombosis
much higher - around eighty times the normal risk.
Prothrombin 20210
Prothrombin is a clotting
factor, and people with the 20210 gene have a change in their
prothrombin which makes the blood clot more easily. About 1 in 50
people of European origin have this gene; it is more common in people
of South European origin. It increases your risk of a venous thrombosis
to twice the normal risk. This is a relatively low risk, so most people
with prothrombin 20210 do not get clots.
Protein C deficiency
Protein C is a natural
anti-clotting chemical in the blood. The deficiency can be genetic, or
due to other conditions such as kidney disease. With inherited protein
C deficiency, the risk of blood clots varies between families, as each
family has a different alteration in the protein C gene. The best guide
to your level of risk is whether you or your relatives have had a
venous thrombosis. If a child inherits two genes with protein C
deficiency (one from each parent - this is very rare), they will have a
more severe problem and will get blood clots in the skin soon after
birth. This is treated with protein C concentrates and anticoagulant
medication.
Protein S deficiency
Protein S is also a
natural anti-clotting chemical in the blood. Protein S deficiency is
rare. The risk of venous thrombosis varies between families, and the
best guide to your risk is to look at whether other relatives have had
a thrombosis.
Antithrombin deficiency
Antithrombin is
another of the natural anti-clotting chemicals in the blood. There are
different types of antithrombin deficiency, both genetic and due to
other diseases. The inherited form is rare, affecting about 1 in 2,000
people.
Antithrombin deficiency is a fairly severe type of
thrombophilia. The risk of a blood clot varies between families, but
can be increased by 25-50 times the normal risk. With this condition,
blood clots can occur not only in the legs or lung, but also in the
veins of the arms, gut, brain or liver. About 1 in 2 people with
antithrombin deficiency get a blood clot before the age of 30, but
others may reach old age without problems.
With this condition,
if you do develop a clot, you may be advised to take long term warfarin
medication. However, this must be decided on an individual basis. Also,
treatment with antithrombin concentrates can be given when there is a
higher risk of clots, for example if you are having major surgery.
With
pregnancy, anticoagulant treatment with heparin is usually needed.
Treatment with antithrombin concentrates can also be used.
Children can have antithrombin deficiency
- parents need to be aware so that they can detect signs of a blood
clot. Although most children don’t get a clot, they are at risk of
clots in situations such as surgery. Also, some newborn babies may get
clots. Anticoagulant treatment or antithrombin concentrate may be
needed. Parents who have antithrombin deficiency themselves and are
expecting a child, should discuss this with their doctor.
Dysfibrinogenaemia
This is a rare genetic
defect where fibrinogen (a clot dissolving chemical) is altered. There
may be increased clotting, increased bleeding or both.
Combined inherited thrombophilias
Some
people inherit more than one thrombophilia gene, for example, factor V
Leiden plus prothrombin 20210. With combined thrombophilias, the risk
of getting a clot is multiplied and there is a much greater risk than
with either condition alone.
Acquired thrombophilias
Acquired thrombophilias are not inherited, and usually start in adulthood.
Antiphospholipid syndrome
This is called APS
for short. It is caused by certain antibodies (immune system chemicals)
in the blood, which are called antiphospholipid antibodies. APS causes
clots in arteries and small blood vessels, as well as venous
thrombosis. In particular, clots may occur in the brain, causing a
stroke.
APS can affect pregnancy in some cases. Many women with
APS do not have problems in pregnancy. However, APS may cause
miscarriage, or other problems - growth restriction of the fetus,
pre-eclampsia or rarely, fetal death. These problems can be reduced by
treatment.
APS can be treated with low-dose aspirin, which is
helpful in pregnancy. If you have had a blood clot, then warfarin is
usually advised instead (or heparin if you are pregnant).
Other acquired conditions
Other medical
conditions can increase the risk of blood clots: some doctors classify
these as thrombophilias. Examples are: certain disorders affecting
blood platelets, some bone marrow disorders, kidney or heart problems,
inflammatory bowel disease and advanced cancer.
Mixed inherited/acquired thrombophilias
These are due to both genetic and non-genetic causes.
Hyperhomocysteinaemia
This is a raised level
of a chemical called homocysteine in the blood, which is thought to
increase the risk of blood clots in arteries and veins because it
damages blood vessels. This is a relatively mild condition, but it can
add to the 'risk factors' for clots. Vitamin B12 and folic acid may
help.
Paroxysmal nocturnal haemoglobinuria
This is
a rare condition affecting the bone marrow. It can lead to venous
thrombosis, often in unusual sites such as the veins of the gut, liver
or brain. Anticoagulation may be needed, and there are other treatments
too for this condition.
Elevated factor VIII
This is pronounced
"factor 8". It is due to abnormally high levels of factor VIII, which
is one of the blood chemicals that promotes clotting. Depending on the
actual level of factor VIII, it can increase the clotting risk by about
six times - this is a relatively low risk for getting a clot.
Further help and information
Lifeblood
A charity dedicated to increasing
awareness and prevention of thrombosis; provides detailed leaflets and
information about many types of thrombophilia.
Tel: 020 7633 9937 Web: www.thrombosis-charity.org.uk
Protein S Deficiency and Thrombophilia
A patient website and forum with information about protein S deficiency.
Web: www.protein.org.uk
References
Disclaimer: This article is for information only and should not
be used for the diagnosis or treatment of medical conditions. EMIS and
PiP have used all reasonable care in compiling the information but make
no warranty as to its accuracy. Consult a doctor or other health care
professional for diagnosis and treatment of medical conditions.
© EMIS and PiP 2008 Updated: 19 Jun 2008
