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Sugar-water hemolysis test

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 low-salt solution.

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 are 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.


There is very 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
  • Hematoma (blood buildup under the skin)
  • Infection (a slight risk any time the skin is broken)

Alternative Names

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


Brodsky RA. Paroxysmal nocturnal hemoglobinuria. In: Hoffman R, Benz EJ Jr, Silberstein LE, et al, eds. Hematology: Basic Principles and Practice. 6th ed. Philadelphia, PA: Elsevier Saunders; 2013:chap 29.

Gallagher PG. Hemolytic anemias. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 161.

Review Date 2/11/2016

Updated by: Todd Gersten, MD, Hematology/Oncology, Florida Cancer Specialists & Research Institute, Wellington, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

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