Introduction Blood
loss leading to anemia is a very common finding in the setting of general practice.
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 the thalassemias (anemias
that are 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 iron 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. Serum ferritin levels that are low are always
an indicator of iron deficiency. If they are 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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