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HAEMOCHROMATOSIS - a patient's guide
Dr Hilary Blacklock - Haematologist, Mercy Specialist Centre
What is it?
Haemochromatosis is a genetic disorder of iron metabolism
very common in those of Celtic, Anglo and Northern European
descent. Absorption of iron through the intestine is uncontrolled
even when body saturation levels have been reached - the
excess iron is very toxic to body organs. The consequences
do not occur until this has been happening for several years.
It is a silent killer eventually causing liver cirrhosis
(and cancer), heart damage, arthritis, diabetes and sexual
dysfunction. Some undiagnosed iron overload sufferers, whose
main symptom is fatigue, take iron tablets for years without
medical advice - these supplements are a serious danger
to people with haemochromatosis.
Early diagnosis and treatment prevents these complications.
Those individuals with no organ damage have a normal life
span Those who already have significantly damaged organs
can have more serious problems and need ongoing monitoring
and treatment, such as insulin for diabetes. Liver cirrhosis
is associated with liver cancer, and ongoing surveillance
is recommended of those so affected as some cancers can
be detected early when surgery or transplant is still possible.
Blood tests that are done to check for haemochromatosis
include an iron saturation test and a serum ferritin. Most
affected (but not all) have an increased iron saturation
of >55% (often expressed as >0.55), and/or a raised serum
ferritin. The former test is more specific - the serum ferritin
can be "falsely" elevated in situations of illness including
infection, inflammation, cancer or liver disease.
Gene Test
There is a mutation in a gene, designated the HFE gene
which can identify most patients with haemochromatosis.
Once this abnormality is found in an individual, the diagnosis
and screening of members of their family is relatively easy.
More than 90% of patients with haemochromatosis are homozygotes
which have two copies of this mutation, having inherited
one from each parent. A heritable, but non-HFE, form of
iron overload occurs in some black populations of African
origin.
Inheritance
Haemochromatosis is common in people of northern European
origin, affecting at least one in 200. More than one in
ten are carriers of the condition, the latter usually without
any clinical consequences. In most cases a genetic abnormality
can be identified. Years ago haemochromatosis probably protected
those who lost a lot of blood in battles or from childbirth.
To inherit two abnormal genes, both parents of an affected
person must have either 1) one copy of the abnormal gene
(they are both carriers or heterozygotes), or 2) one is
a carrier and the other has haemochromatosis, or 3) both
parents can have haemochromatosis. Children of an affected
person are all at least carriers. If the second parent is
a carrier, 50% will have haemochromatosis.
Suspected Haemochromatosis
Of those with abnormal iron tests (iron saturation > 0.55
and/or a raised serum ferritin), many will be homozygous
with two copies of the HFE gene mutation. The gene test
is useful in making the initial diagnosis, as well as detecting
other affected family members. The 10% of cases without
the common gene mutation have other genes or factors - some
are unidentified as yet. In those diagnosed on blood iron
studies and/or clinical findings with a negative gene test,
a liver biopsy should be done to help confirm the diagnosis
and to exclude liver cirrhosis. A liver biopsy is not needed
in those with the mutation to make the diagnosis, but is
done in those with a very high ferritin level and/or abnormal
liver tests to check for liver damage.
Family Screening
First-degree relatives (parents, brothers, sisters, children)
of an affected person with the HFE mutation should be screened
with iron studies (saturation, serum ferritin) and the gene
test. The latter is particularly useful in identifying young
people who may be affected but as yet have normal iron tests.
Population Screening
Patient support groups have welcomed the gene test and
have pushed for screening of populations at risk. However,
the presence of the gene mutation does not always correlate
with disease expression. There are other genetic or environmental
factors, which contribute to the amount of iron loaded and
any clinical consequences. Before the gene test was available,
it was recommended that first degree relatives with normal
Fe studies had iron tests repeated every 3 to 5 years. Obviously
in a family known to have the HFE gene, the testing of other
members is important and easy.
Mass screening of Europeans using iron saturation and/or
ferritin tests has been proposed and is controversial. Some
are dubious that such an approach would be cost effective.
Others believe that the testing would prevent expensive
end-stage treatments and save lives. Studies aimed at providing
information re: screening are currently underway. Certainly
those found to have increased iron saturation and ferritin
should have the gene test performed. Those with liver disease
and/or arthritis, unexplained heart disease, diabetes or
cirrhosis should also be tested.
Treatment
Treatment is life long, but is usually relatively simple.
The aim is to reduce the total amount of body iron and then
to maintain a low iron level to prevent further damage (ferritin
less than 100Ug/L). This is done by regular blood removal
(also known as phlebotomy or venesection), with monitoring
of blood ferritin levels. Each ml of blood removed contains
approximately 1 mg of iron - the body replaces the blood
by drawing iron from the tissues. The amount of blood removed
at each session should be no more than 10% of the blood
volume (8mls/kg), and may need to be less in those with
bad heart disease such as angina. How many treatments needed
will depend on the rate of blood replacement and the severity
of the iron overload. It is important to remove the excess
iron as quickly as possible to switch off ongoing organ
damage, so initially venesections should be done once or
twice weekly if tolerated. Once the iron levels are low,
venesections are then needed three or four times a year
to maintain the body iron at a safe level.
A normal diet can then be eaten, although excessive red
meat and liver should be avoided. For those with iron overload,
iron tablets and vitamin C supplements which increase iron
absorption should be avoided, as well raw oysters and other
shellfish which can transmit a dangerous organism.
Blood Donation
It is very likely that as many as one in 200-blood donors
has undiagnosed early haemochromatosis and that their blood
is currently being transfused safely. However in some countries,
healthy people with haemochromatosis are retired as blood
donors when the diagnosis is made. The concern when there
is a financial charge for therapeutic venesections relates
to the fact that the desire to donate blood is then not
entirely altruistic. Other blood services allow those with
early-uncomplicated haemochromatosis to donate as long as
all other donor criteria are fulfilled.
Haemochromatosis Support Groups
There are support groups who can provide information to
people with haemochromatosis and to general practitioners
- ask the specialist in your area for the address.
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