Sugar-water hemolysis test

Definition

The sugar-water hemolysis test is a blood test to detect fragile red blood cells. It does this by testing how well they withstand swelling in a sugar (sucrose) solution.

Alternative Names

Sucrose hemolysis test; Hemolytic anemia sugar water hemolysis test; Paroxysmal nocturnal hemoglobinuria sugar water hemolysis test; PNH sugar water hemolysis test

How the Test is Performed

A blood sample is needed.

How to Prepare for the Test

There is no special preparation needed for this test.

How the Test will Feel

When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.

Why the Test is Performed

Your health care provider may recommend this test if you have signs or symptoms of paroxysmal nocturnal hemoglobinuria (PNH) or hemolytic anemia of unknown cause. Hemolytic anemia is a condition in which red blood cells die before they should. PNH red blood cells are very likely to be harmed by the body's complement system. The complement system consists of proteins that move through the bloodstream. These proteins work with the immune system.

Normal Results

A normal test result is called a negative result. A normal result shows that less than 5% of red blood cells break down when tested. This breakdown is called hemolysis.

A negative test does not rule out PNH. False-negative results may occur if the fluid part of blood (serum) lacks complement.

Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your provider about the meaning of your specific test results.

What Abnormal Results Mean

A positive test result means the results are abnormal. In a positive test, more than 10% of red blood cells break down. It could indicate the person has PNH.

Certain conditions can make the test results appear positive (called false positive). These conditions are autoimmune hemolytic anemias and leukemia.

Risks

There is little risk involved with having your blood taken. Veins and arteries vary in size from one person to another and from one side of the body to the other. Taking 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 lightheaded
• Multiple punctures to locate veins
• Hematoma (blood buildup under the skin)
• Infection (a slight risk any time the skin is broken)

References

Araten DJ, Brodsky RA. Paroxysmal nocturnal hemoglobinuria. In: Hoffman R, Benz EJ, Silberstein LE, eds. Hematology: Basic Principles and Practice. 8th ed. Philadelphia, PA: Elsevier; 2023:chap 32.

Elghetany MT, Banki K. Erythrocytic disorders. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 33.

Gallagher PG. Hemolytic anemias: red blood cell membrane and metabolic defects. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 147.