A sugar-water hemolysis test, also known as a sucrose hemolysis test, is used to detect fragile red blood cells.
When your red blood cells are put into a sugar-water solution, it is possible to see their ability to withstand swelling. If they swell and burst, they are considered more fragile than normal.
Analysis of how many cells burst can help assess the state of your red blood cells and allow your doctor to diagnose your disorder.
Most often, your doctor will recommend a sugar-water hemolysis test if you have symptoms of the following disorders:
This is a condition where there are too few red blood cells in your body because they are destroyed too early and the bone marrow is unable to replace them. There are several types of hemolytic anemia.
Symptoms include chills, dark urine, fatigue, fever, rapid heart rate, shortness of breath, an enlarged spleen, and a pale or yellow skin color.
Paroxysmal Nocturnal Hemoglobinuria (PNH)
PNH is a rare blood disease in which red blood cells are destroyed too early because your body lacks a certain gene called PIG-A.
Symptoms of PNH include abdominal pain, back pain, blood clots, dark urine, headache, shortness of breath, and easy bruising or bleeding.
The process of taking a blood sample for testing is called venipuncture. This is just a medical term for the standard drawing of blood.
You may need to fast—or refrain from eating or drinking—for some time before the blood test. Be sure to check with your doctor if there are any specific pre-test preparations you need to make.
During the test, your doctor will take blood from one of your veins, usually from one at your inner elbow or back of your hand. First, your doctor will sterilize the area with an antiseptic. Then, he or she will wrap an elastic band around your arm to apply pressure and help the veins to swell with blood.
Once the vein swells, your doctor will insert a sterile needle directly into the vein. The blood will collect into an attached tube. Once enough blood has been collected for the sample, the plastic band is untied and the needle is removed from your vein. The site of the needle insertion will be cleaned and bandaged if it is bleeding.
For infants or young children, your doctor or nurse might simply make a small cut on their skin to allow blood to come to the surface. A test strip or slide will then be used to collect a small sample of the blood, and the area will be cleaned and bandaged.
In some cases, a simple finger prick will provide enough blood for the test. In that case, your finger would be pricked with a needle and the blood would come to the surface. Your doctor (or nurse) collects a sample of that blood, then cleans and bandages your finger.
Once it has been collected, the blood is sent to the laboratory to be analyzed.
In a normal test, less than five percent of the red blood cells will break down (hemolysis). However, normal levels vary at different laboratories.
A positive, or abnormal result, means more than 10 percent of your red blood cells broke down (hemolysis). This result may mean you may have PNH. Forms of autoimmune hemolysis anemia or leukemia can also cause the test to have false positives or abnormal results.
Other tests may be necessary to confirm what is causing your red blood cells to break down, and to plan for treatment.
There are risks from a sugar-water hemolysis test. Any time blood is drawn, you have a slight risk of:
- pain and discomfort (sometimes veins are hard to access)
- fainting or lightheadedness
- blood accumulating under your skin (hematoma or bruising)