Is a Serum Hemoglobin Test?
A serum hemoglobin test measures
the amount of free-floating hemoglobin in your blood serum. Serum is the liquid that is left
over when the red blood cells and the clotting elements have been removed from
your blood plasma. Hemoglobin is
a type of oxygen-carrying protein found in your red blood cells.
Normally, all of the hemoglobin in your body is contained in your
red blood cells. However, some conditions may cause some of the hemoglobin to
be in your serum. This is called free
hemoglobin. The serum hemoglobin test measures this free hemoglobin.
Doctors usually use this test to diagnose or monitor abnormal
breakdown of red blood cells. If you have had a recent blood transfusion, this
test can monitor for a transfusion reaction. Another cause might be hemolytic anemia. If you have this
type of anemia, your red blood cells break down too quickly. This leads to
higher-than-normal levels of free hemoglobin in your blood.
The test is sometimes called a blood hemoglobin test.
Is a Serum Hemoglobin Test Ordered?
Your doctor may order a serum hemoglobin test if you are
exhibiting symptoms of hemolytic anemia. This condition occurs when your red
blood cells break down rapidly and your bone marrow can’t replace them quickly
Your doctor may also order this test if you have already been
diagnosed with hemolytic anemia. In this case, the test can help your doctor
monitor your condition.
Is Hemolytic Anemia?
There are two types of hemolytic anemia.
Extrinsic hemolytic anemia
If you have extrinsic
hemolytic anemia, your body produces normal red blood cells. However,
they are destroyed too quickly because of an infection, an autoimmune disorder,
or a particular type of cancer.
Intrinsic hemolytic anemia
If you have intrinsic
hemolytic anemia, your red blood cells themselves are defective and
naturally break down quickly. Sickle cell anemia,
spherocytic anemia, and G6PD
deficiency are all conditions that can lead to hemolytic anemia.
Both types of hemolytic anemia cause the same symptoms. However,
you may have additional symptoms if your anemia is caused by an underlying
In the early stages of hemolytic anemia, you may feel:
You may also experience headaches.
As the condition progresses, your symptoms will become more
serious. Your skin may become yellow or pale, and the whites of your eyes may
become blue or yellow. Other symptoms may include:
- brittle nails
- heart issues (an increased heart rate or heart
- dark urine
- an enlarged spleen
- an enlarged liver
- tongue soreness
Is the Test Administered?
A serum hemoglobin test requires a small sample of blood to be
drawn from your hand or your arm. This process usually only takes a few
- Your doctor or nurse will apply an antiseptic to
the area where your blood will be drawn.
- An elastic band will be tied around your upper
arm to increase the amount of blood flow to the veins, causing them to swell.
This makes it easier to find a vein.
- Then, a needle will be inserted into your vein. After
the vein is punctured, the blood will flow through the needle into a small tube
that’s attached to it. You may feel a slight prick when the needle goes in, but
the test itself isn’t painful.
- Once enough blood is collected, the needle will
be removed and a sterile bandage will be applied over the puncture site.
Collected blood is then sent to a lab for testing.
Hemoglobin Test Results
Serum hemoglobin is measured in grams of hemoglobin per deciliter
of blood (mg/dL). Lab results vary so your doctor will help determine if your
results are normal or not. If your results come back normal, your doctor may
want to do further testing.
High levels of hemoglobin in your serum are generally a sign of
hemolytic anemia. Conditions that can cause red blood cells to break down
abnormally include, but are not limited to:
- sickle cell anemia: a genetic disorder that
causes your red blood cells to be rigid and unusually shaped
- G6PD deficiency: when your body does not make
enough of the enzyme that produces red blood cells)
- hemoglobin C disease: a genetic disorder that
leads to the production of abnormal hemoglobin
- thalassemia: a genetic disorder that affects
your body’s ability to produce normal hemoglobin
- congenital spherocytic anemia: a disorder of
your red blood cell membranes
If the results of your test are abnormal, your doctor will
probably perform more tests to determine exactly what is causing hemolytic
anemia. These additional tests may be simple blood or urine tests, or they may
involve testing your bone marrow.
of the Serum Hemoglobin Test
The only risks involved in this test are those always associated
with a blood draw. For example, you will probably experience slight pain when
the needle is inserted to draw your blood. You might bleed a little when the
needle is removed or develop a small bruise in the area.
Rarely, a blood draw may have more serious consequences, such as
excessive bleeding, fainting, or an infection at the puncture site.