Iron Overload (Hemochromatosis) ... To Screen or Not to Screen?
July has been designated Hemochromatosis Screening Awareness Month
in the United States but the question all year long everywhere in the
world is: Whether to screen or not to screen? That is the question
that divides the health care professionals who care for people with
hemochromatosis, a disorder commonly called iron overload.
If not recognized and treated, iron overload can have dire
consequences such as scarring of the liver (cirrhosis),
diabetes, and heart failure.
The means to screen for iron overload are available. But they are
not being used. Why? Because there is disagreement about whether
screening should be done.
Some Areas of Agreement
There are several areas of agreement about iron overload
(hemochromatosis). The condition is due to an inability to regulate iron
absorption. Too much of the iron in food is
absorbed from the intestine and passes into the blood stream. The
extra iron accumulates in organs ever so slowly. Someone with
hemochromatosis may typically have chemically detectable iron
overload by age 30 but not experience even the first signs or
symptoms of the disease (such as unusual weakness and fatigue,
weight loss, bronzed skin (not caused by sunlight), joint and
abdominal pains, impotence in men, and cessation of menstrual periods
in women) until they are past 40.
There is also no disagreement about the genetic basis of
hemachromatosis. About 1 in 9 people carries a gene for
hemochromatosis but never develops the disease (although they can pass
the gene along to their children) each child of a carrier
runs a 25% risk of inheriting both of their hemochromatosis genes and
joining the 1 in 300 Americans estimated to have the disease.
Gene Raises Screening Questions
A sensitive and relatively inexpensive screening test for iron
overload has long been available in the form of what is called the
transferrin saturation (TS) test. Two positive TS test results (above 60% in
men or 50% in women) are suggestive of hemochromatosis. The diagnosis
then must be confirmed, most commonly by a liver biopsy or systematic
bloodletting to extract iron, a technique termed quantitative phlebotomy.
What started the controversy brewing over screening was the
identification of the gene responsible for most cases of iron
overload. The key research had begun in 1976 when it was recognized
that there might possibly be an association between the
hemochromatosis gene and the major transplantation genes (called
HLA). The hemochromatosis gene was finally found in 1996. The symbol
for the gene is HLA-H (HLAE) or, now preferably, HFE.
Once the HFE gene was identified, a test for it was
devised and questions arose in earnest about the prospect of massive
public health screenings for hemochromatosis.
Patients with the disease see an average of three doctors
before being correctly diagnosed, according to the Centers for
Disease Control (CDC). Advocates say screening could be a useful tool
for identifying and treating the disease early.
What the Expert Panel Said
In March of 1997, the CDC and the National Human Genome Research
Institute, part of NIH, convened an expert panel. The panel evaluated
the potential of hemochromatosis screening. A report of their
recommendations was published in July of 1998 in
the Journal of the American Medical Association (JAMA).
The expert panel recommended against screening large populations
for the disorder. Their recommendation was based on lack of
information about how the gene is distributed within populations, how it affects different
people, how the disease progresses, and how to care for people who
have mutations of the gene but have no signs or symptoms of
the disease. The panel also raised the issues of discrimination and
stigmatization of people with the gene. They concluded that
population-based research needs to be conducted to learn more about
the disorder and how genes (and the environment) interact to cause
the disorder to progress differently or not at all in some people.
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