Blood Tests and Procedures Used for Stroke Diagnosis
f
you are being evaluated for stroke, it is likely that
your doctor will order some blood tests. Stroke cannot
be diagnosed by a blood test alone. However, these tests
can provide information about stroke
risk factors and other medical problems which may
be important.
Please note that the first set of tests
are commonly used for routine or emergency evaluation
of stroke, while the others are used only in very specific
situations. Unless otherwise noted, each of these tests
require just one tube of blood (a few teaspoons) drawn
from a vein.
Commonly
Used Blood Tests
CBC
(Complete blood count)
This is a routine test to determine the number
of red blood cells, white blood cells, and platelets
in your blood. Hematocrit and
hemoglobin are measures of the number of
red blood cells. A complete blood count
might be used to diagnose anemia (too little blood)
or infection (shown by too many white blood cells).
Coagulation
tests PT (Prothrombin time)
PTT (Partial thromboplastin time)
INR (International normalized ratio)
These tests measure how quickly your blood clots.
An abnormality could result in excessive bleeding
or excessive clotting (which is difficult to measure).
If you have been prescribed a blood-thinning medicine
such as warfarin (Coumadin or similar drugs),
the INR is used to be sure that you receive the
correct dose. It is very important that
you obtain regular checks. If you are taking
heparin, the PTT (or aPTT) test is used to determine
the correct dose.
Blood
chemistry tests
These tests measure the levels of normal chemical
substances in your blood. The most
important test in emergency stroke evaluation
is glucose (or blood sugar), because levels of
blood glucose which are too high or too low can
cause symptoms which may be mistaken for stroke.
A fasting blood glucose is used to help in the
diagnosis of diabetes, which is a risk factor
for stroke. Other blood chemistry tests measure
serum electrolytes, the normal ions in
your blood (sodium, potassium, calcium) or check
the function of your liver or kidneys.
Blood
lipid tests
Cholesterol, total lipids, HDL, and LDL
Elevated cholesterol (particularly "bad"
cholesterol, or LDL) is a risk factor for heart
disease and stroke. Click here to learn
more about cholesterol
and cardiovascular risks from the National
Institutes of Health.
Blood Tests for Specific Situations
This is a partial list of less common blood tests
sometimes ordered for specific stroke situations,
or where the cause of stroke is unclear (for example,
in a young person without known stroke risk factors).
Abnormal results may suggest a cause for the stroke.
Coagulation
factors: Antithrombin III, Protein C, Protein
S; Factor VIII; activated Protein C resistance
(Factor V Leiden)
Erythrocyte
sedimentation rate (ESR)
Hemoglobin
electrophoresis
Homocysteine
Syphilis
serology (VDRL, FTA, others)
Toxicology
screen (serum or urine )
Please note that this chart applies
only to the use of these tests for stroke diagnosis.
Be sure to discuss any questions
or concerns with your doctor or health care provider.
The information contained in this
web site is not a substitute for medical advice or treatment.
Consultation with your doctor or health care professional is recommended.
About Stroke
f
you are being evaluated for stroke, it is likely that
your doctor will order some blood tests. Stroke cannot
be diagnosed by a blood test alone. However, these tests
can provide information about 
CBC
(Complete blood count)
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