How Is Iron-Deficiency Anemia Diagnosed?
Iron-deficiency anemia is diagnosed using a person's
medical history, a physical exam, and diagnostic tests and procedures. A doctor
can use these methods to determine how severe the anemia is, its cause, and
appropriate treatment. Mild to moderate anemia may have no signs or symptoms.
In fact, anemia is often discovered unexpectedly on screening tests and when
doctors are checking for other problems.
Specialists Involved
Primary care doctors often diagnose and treat
iron-deficiency anemia. These doctors include pediatricians, family doctors,
obstetricians, or internal medicine specialists. Other doctors may be
consulted, such as experts on diseases of the blood (hematologists) or experts
on diseases of the digestive system (gastroenterologists).
Medical and Family History
To find the cause of the anemia and how severe it
is, the doctor may ask detailed questions about symptoms (see the
What Are the Signs and Symptoms of
Iron-Deficiency Anemia? section). The doctor may ask whether the person or
a family member has ever had problems with
anemia. The doctor will ask about
things that may cause anemia, including illnesses, conditions (such as
pregnancy), and medicines. The doctor also may ask about the person's diet and
eating habits.
Physical Exam
A physical exam may include:
- Checking for pale or yellowish skin, gums, or
nail beds
- Listening to the heart for a rapid or irregular
heartbeat
- Listening to the lungs for rapid or uneven
breathing
- Feeling the abdomen to check the size of the
liver and spleen
- Checking for signs of bleeding, including a
pelvic and rectal exam (these areas are common sources of blood loss)
The doctor also will order a number of tests or
procedures to be sure about the type of anemia and how severe it is.
Diagnostic Tests and Procedures
Your doctor may order various tests or procedures to
determine the type and severity of anemia you have. Usually, the first test
used to diagnose anemia is a complete blood count (CBC). The CBC tells a number
of things about a person's blood, including:
- The hemoglobin level. Hemoglobin is the iron-rich
protein in red blood cells that carries oxygen through the body. The normal
range of hemoglobin levels for the general population is 11.1-15.0 g/dL. A low
hemoglobin level means a person has anemia.
- The hematocrit (hee-MAT-oh-crit) level. The
hematocrit level measures how much of the blood is made up of red blood cells.
The normal range for hematocrit levels for the general population is 32-43
percent. A low hematocrit level is another sign of anemia.
The normal range of these levels may be lower in
certain racial and ethnic populations. Your doctor can explain your individual
test results.
The CBC also checks:
- The numbers of red blood cells. Too few red blood
cells means a person has anemia. A low number of red blood cells is usually
seen with either a low hemoglobin or a low hematocrit level, or both.
- The numbers of white blood cells. White blood
cells are involved in fighting infection.
- The number of platelets in the blood. Platelets
are small cells that are involved in blood clotting.
- Red blood cell size. The mean cell volume
measures the average size (volume) of red blood cells. In iron-deficiency
anemia, the red blood cells are often smaller than normal.
If the CBC results confirm that you have anemia,
your doctor may order additional tests to determine the cause, severity, and
correct treatment for your condition. For example, the doctor may order a
reticulocyte (re-TIK-u-lo-site) count. Reticulocytes are young red blood cells.
This test measures the number of new red blood cells in your blood. The
reticulocyte test is used to determine whether your bone marrow is producing
red blood cells at the proper rate.
Tests That Measure Iron Levels in the Body
Iron is needed to make hemoglobin-the protein in red
blood cells that gives them their color and carries oxygen. Several tests can
be used to check the level of iron in the blood and in the body:
- Serum iron. This test measures the amount of iron
in the blood. The level of iron in the blood can be normal even when the total
amount of iron in the body is low. For this reason, other iron tests are
done.
- Serum ferritin. Ferritin is a protein that helps
store iron in the body. Results of this test give doctors a good idea of how
much of the body's stored iron has been used up.
- Transferrin level or total iron-binding capacity.
Transferrin is a protein that carries iron in the blood. Total iron-binding
capacity measures how much of the transferrin in the blood is not carrying
iron. People with iron-deficiency anemia have a high level of transferrin that
has no iron.
- Other blood tests. Other tests the doctor may
order include tests that check hormone levels, especially the thyroid hormone.
Blood tests also may be ordered to check the level of a chemical used by the
body to make hemoglobin. It is called erythrocyte protoporphyrin.
Tests That Diagnose Gastrointestinal Bleeding
If your doctor suspects anemia because of internal
bleeding in the stomach or intestines, several tests may be used to discover
the source of the bleeding.
One of the first tests ordered is the fecal occult
blood test. This test checks the stool for signs of blood. It can detect even
small amounts of bleeding anywhere in the intestines. If blood is found in the
stool, further tests may be used to find the source of the bleeding,
including:
- Colonoscopy. In this test, a thin, flexible tube
attached to a video camera is used to examine the rectum and colon for sources
of bleeding.
- Upper GI endoscopy. In this test, a thin,
flexible tube attached to a video camera is used to examine the stomach and
upper intestines. The doctor looks for signs of bleeding.
- Pelvic ultrasound. This test uses sound waves to
look at the uterus and other pelvic organs. It checks for causes of heavy
vaginal bleeding, such as fibroids.
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