MedlinePlus Medical Encyclopedia: Sugar-water hemolysis test

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Sugar-water hemolysis test

Contents of this page:
Alternative names Definition How the test is performed How to prepare for the test How the test will feel	Why the test is performed Normal Values What abnormal results mean What the risks are Special considerations

Alternative names

Sucrose hemolysis test

Definition Return to top

This is a blood test to detect increased fragility of red blood cells by swelling them in low-salt solution.

How the test is performed Return to top

Blood is drawn from a vein, usually on the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and an elastic band is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the band to swell with blood.

A needle is inserted into the vein, and the blood is collected in an airtight vial or a syringe. During the procedure, the band is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

For an infant or young child, the area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.

The blood is analyzed in a laboratory.

How to prepare for the test Return to top

There is no special preparation needed for this test.

For infants and children, the preparation you can provide for this test depends on your child's age and previous experience. For general information regarding how you can prepare your child, see the following topics:

infant test or procedure preparation (birth to 1 year)
toddler test or procedure preparation (1 to 3 years)
preschooler test or procedure preparation (3 to 6 years)
schoolage test or procedure preparation (6 to 12 years)
adolescent test or procedure preparation (12 to 18 years)

How the test will feel Return to top

When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the test is performed Return to top

This test is ordered for suspected paroxysmal nocturnal hemoglobinuria (PNH), and for any hemolytic anemia of unkown origin. PNH red blood cells are unusually susceptible to complement (a component of the body's defense mechanism).

When a low-salt solution containing sucrose (sugar) is added to these cells, the complement is activated, binds to the cells, and bursts them.

Normal Values Return to top

negative: less than 5% hemolysis (red blood cell breakdown)
positive: greater than 10% hemolysis

What abnormal results mean Return to top

paroxysmal nocturnal hemoglobinuria (PNH)
autoimmune hemolytic anemias and leukemia may give false positive result

What the risks are Return to top

Risks associated with having blood drawn are slight:

excessive bleeding
fainting or feeling light-headed
hematoma (blood accumulating under the skin)
infection (a slight risk any time the skin is broken)
multiple punctures to locate veins

Special considerations Return to top

A negative test does not rule out PNH. False-negative results may occur if the serum is depleted of complement.

Update Date: 9/14/2003

Updated by: Corey Cutler, M.D., M.P.H., F.R.C.P.C., Department of Medical Oncology, Dana-Farber Cancer Institute; Instructor in Medicine, Harvard University, Boston, MA. Review provided by VeriMed Healthcare Network.

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