Encyclopedia of Health and Medicine

anemia 125
Erythrocyte destruction or deformity One of
the spleen’s roles is to filter erythrocytes from the
blood that are old or defective, a normal process
called HEMOLYSIS that maintains an appropriate balance
of erythrocytes in the blood. The spleen may
inappropriately sequester and destroy healthy erythrocytes,
sometimes without apparent reason.
SICKLE CELL DISEASE is a complex genetic disorder
that results in malformed erythrocytes, causing
anemia among other symptoms. In THALASSEMIA,
another genetic disorder, erythrocytes are normal
but hemoglobin is defective.
Inadequate erythropoiesis Nutritional deficiencies
and renal failure are the leading causes of
diminished erythropoiesis. The bone marrow
requires vitamin B 12 , iron, and folic acid to manufacture
erythrocytes. Pernicious anemia results
when the STOMACH fails to produce intrinsic factor,
a substance necessary to absorb vitamin B 12 from
ingested foods. When these vital NUTRIENTS are
lacking, the bone marrow cannot generate new
erythrocytes. Iron deficiency anemia is the most
common type of anemia in the United States.
Kidney disease and RENAL FAILURE also affect
erythropoiesis because the KIDNEYS secrete ERY-
THROPOIETIN (EPO), the HORMONE that stimulates the
bone marrow to produce erythrocytes. Bone marrow
disorders such as myelofibrosis and MULTIPLE
MYELOMA also disturb HEMATOPOIESIS. Aplastic anemia
is a life-threatening type of anemia that
results when the bone marrow completely shuts
down blood cell production.
COMMON CAUSES OF ANEMIA
adverse DRUG reactions
CHEMOTHERAPY
chronic HEPATITIS
CIRRHOSIS
DYSMENORRHEA
environmental toxins
folic acid deficiency
GALLBLADDER DISEASE
GASTROINTESTINAL BLEEDING
HEMOLYSIS
hemorrhage
HIV/AIDS
INFLAMMATORY BOWEL DISEASE (IBD) iron deficiency
LEUKEMIA
lymphoma
MALABSORPTION syndromes
MULTIPLE MYELOMA
MYELODYSPLASIA SYNDROME
MYELOFIBROSIS
PREGNANCY
RADIATION THERAPY
RENAL FAILURE
SICKLE CELL DISEASE
SYSTEMIC LUPUS ERYTHEMATOSUS (SLE) THALASSEMIA
vitamin B 12 deficiency
Symptoms and Diagnostic Path
Many people do not have symptoms of anemia
but instead find out they have anemia through
blood tests conducted for other reasons, such as
during ROUTINE MEDICAL EXAMINATION or screening
for BLOOD DONATION. When symptoms are present,
they are generally the same regardless of the
underlying cause and commonly include
• tiredness and fatigue
• breathlessness, especially with physical exercise
• HEADACHE
• chronically cold or tingling hands and feet
• PALPITATIONS or ARRHYTHMIA (irregular or rapid
heartbeat)
• irritability
• paleness of the SKIN, nail beds, and gums
Hemolytic anemia may also cause JAUNDICE.
Severe anemia can be debilitating, preventing an
individual from participating even in everyday
activities. Such severe anemias generally result
from serious underlying health circumstances.
Diagnostic blood tests including complete blood
count (CBC), hemoglobin, and hematocrit often
provide the initial diagnosis. Further tests might
include bone marrow biopsy to determine
whether the bone marrow is adequately producing
erythrocytes or whether the erythrocytes are
normal. The doctor may choose to perform other
diagnostic procedures, depending on the findings.
Whether or not the anemia causes symptoms, it is
important to find its cause.
Treatment Options and Outlook
Most types of anemia are curable or treatable.
Treatment targets the underlying cause of the anemia.
Supplemental iron, vitamin B 12 , and folic
acid can improve many types of anemia. Pernicious
anemia requires lifetime injections of vitamin
B 12 . Aplastic anemia or anemia due to
chronic health conditions may require BLOOD
TRANSFUSION or BONE MARROW TRANSPLANTATION. Doctors
may treat chronic anemia or transient anemia
due to cancer treatment with EPO supplementation.
Anemia resulting from GENETIC DISORDERS
such as sickle cell disease or thalassemia requires
ongoing treatment. Successful treatment of the