Cryoglobulins are abnormal proteins. This article describes the blood test used to check for them.
In the laboratory, cryoglobulins come out of blood and form crystals when the blood sample is cooled below 98.6 degrees Fahrenheit (37 degrees Celsius).
Cryoglobulins come in three main types, but in 90% of cases the cause is
How the test is performed
Blood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.
Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm.
Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.
In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.
Because they are temperature sensitive, cryoglobulins are very hard to accurately detect. The blood specimen must be collected in a special way and the test should only be done in laboratories that are equipped for it.
How to prepare for the test
There is no special preparation for this test.
How the test will feel
Some people feel discomfort when the needle is inserted. Afterward, there may be some throbbing.
Why the test is performed
This test is most often done when a person has symptoms of a condition associated with cryoglobulins. Cryoglobulins are associated with cryoglobulinemia. They also occur in other conditions that affect the skin, joints, kidneys, and nervous system.
Normally, there are no cryoglobulins.
Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
The example above shows the common measurement for results for these tests. Some laboratories use different measurements or may test different specimens.
What abnormal results mean
A positive test may indicate:
- Hepatitis (especially hepatitis C)
Lymphoma Macroglobulinemia – primary Multiple myeloma Rheumatoid arthritis Systemic lupus erythematosus
Additional conditions under which the test may be performed:
What the risks are
Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining blood from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight, but may include:
- Excessive bleeding
- Fainting or feeling light-headed
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)