Anemia
Due to Blood Loss Introduction Blood loss
leading to anemia is a very common finding in the setting of general practice.
Anemia Due to Blood Loss: Anemias
Caused By Acute Blood Loss Chronic
Blood Loss Anemia Iron
Deficiency When the physician spots a person with anemia and the
blood tests show a microcytic anemia, the question is whether this is due to an
acute blood loss or due to chronic blood loss. These two syndromes are two very
different clinical conditions, that’s why they are dealt with here under two
different headings. For one thing: an acute blood loss can lead to destabilization
of the circulation very quickly resulting in shock and will need very aggressive
treatment, while an anemia from chronic blood loss allows the physician more time
for a diagnostic work-up. On the other hand anemia due to chronic blood loss may
be due to a more sinister cause such as cancer.
Anemias Caused By Acute Blood Loss This
type of anemia is the result of a massive hemorrhage. Trauma to a large blood
vessel and a massive hemorrhage can be the reason, on the other hand erosion of
a blood vessel by a disease like a duodenal or stomach ulcer. With the use of
blood thinners there may be a failure of bleeding to stop, a condition which can
occur when a patient receives blood thinners for prevention of blood clots or
as a precaution when irregular heart beats are present. Sudden loss of one third
of the blood volume may be fatal. Hemorrhage at a rapid pace causes more severe
symptoms than a slower bleed. Despite the symptoms of dizziness, faintness, sweating
and rapid pulse, the red blood count, hemoglobin and hematocrit may be high, because
of the constriction of blood vessels. Within a few hours, the body attempts to
replace the missing blood volume with tissue fluid, and at this point there will
be a drop in the red blood count and the hemoglobin. As there is no change in
the structure of the red blood cells, the anemia is called normocytic. Treatment
The immediate necessity is the attempt to stop the bleeding (repair of
a torn blood vessel). The blood volume has to be restored. Treatment for shock
may be necessary. Infusions of plasma are the most suitable substitute for blood.
Saline solution or dextrose solutions only have temporary benefits. The patient
needs absolute rest and should receive fluids and other supportive treatment for
shock. In addition iron supplement can be used to replace the iron that has been
lost during the hemorrhage. When a large amount of blood has been lost in a short
time, whole blood transfusions may be necessary.
Chronic Blood Loss Anemia Causes
This type of anemia may be caused by a prolonged moderate blood loss. A
bleeding stomach ulcer or hemorrhoids can be the culprits. Bleeding in the urinary
tract or in female patients bleeding from the uterus can be the source of a microcytic
anemia. Early changes in laboratory tests can be minimal. Under the microscope
the blood cells look small; this is due to a chronic lack of iron. Differential
Diagnosis There are different types of anemia besides the picture
of microcytic anemia, including iron deficiency anemia, iron transport deficiency,
iron utilization anemias, anemia of chronic disease, and thalassemia (anemia caused
by defective hemoglobin synthesis.)
Iron Deficiency In iron deficiency anemia
the iron metabolism is disturbed. Normally the total body iron amounts to about
3.5 g in healthy males and 2.5 g in healthy adult females. Iron storage occurs
in tissue cells as ferritin and hemosiderin. The average North American diet is
normally adequate to meet the iron demands of the body. Iron is best absorbed
if the food source contains the "heme Fe", iron that comes from a meat
source. Non-heme Fe is frequently not as well absorbed, because some food items
like bran and tannates in tea can reduce the absorption. Ascorbic acid (vitamin
C) is the only food element known that increases the bioavailability of non-heme
Fe (iron from plant sources). Of about 10mg/day of dietary iron, adults only absorb
1mg. Because iron absorption is so limited, the body has a mechanism to conserve.
Aging red blood cells are undergoing a process called phagocytes by mononuclear
phagocytes. It means that an old red blood cell is "recycled" to make
the iron content available to the body. By this reutilization of iron about 97%
if the daily needs for iron are met from this storage pool. Diagnostic
Tests It is obvious that only laboratory tests will give information
about the iron level and iron binding capacity. If the concentration of serum
iron is low, it is a sign of iron deficiency and chronic disease. Elevated iron
levels point to hemolytic conditions and iron overload disorders. Patients who
are taking iron pills may have a normal serum iron level and yet have a deficiency.
A valid test can only be done, if iron therapy is stopped for 1 to 2 days. In
iron deficiency the iron binding capacity is increased: the body struggles to
get more iron. In anemia of chronic disease iron binding capacity is decreased.
Ferritin levels that are low are always an indicator of iron deficiency. If ferritin
is elevated, disease of the liver like hepatitis or some tumors, especially acute
leukemia, Hodgkin's disease and tumors of the gastro-intestinal area may be present.
Other items that are monitored are the serum transferrin receptor, red blood cell
ferritin and free red blood cell protoporphyrin. Here is an illustration of the
complex transferrin
system. Laboratory medicine in the area of blood disorders
is extremely complex and laboratory methods have become sophisticated. As a result
the input of a hematologist who specializes in the diagnosis and treatment of
the multitude of blood disorders is often needed.
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