Hemolysis:
What is it and How to Prevent it.
Red is such a pretty color... unless it tinges the serum or plasma of the specimen you collected. Then it's ugly. It's ugly because it usually means the time you spent drawing the specimen was wasted and the draw will have to be repeated. But it's more than a time killer. Having to recollect a hemolyzed specimen that is incapable of rendering accurate and useful results to the physician delays treatment, diagnosis, and/or much-needed medications. In critical situations, time isn't just money, it can be life itself. Hemolysis has been reported to be the number one cause of rejected chemistry specimens. In fact, six times more specimens are rejected because of hemolysis than the second-most common reason, insufficient sample volume. But before we master the art of preventing hemolysis, we have to understand how it occurs. "Hemo" means blood, of course; "lysis" means to rupture or the destruction of cells. So hemolysis is literally the destruction of blood cells, specifically red blood cells. When red cells rupture, they spill their contents, mostly hemoglobin, into their surroundings. Hemoglobin is a respiratory pigment that has an insatiable passion for oxygen and gloms onto every molecule it can hold while passing through the lungs, then dumps it off into the tissue where it's needed for cellular functions. Hemoglobin is also what makes blood red. So naturally, when red cells burst, it tinges the liquid portion of the blood. If red cells burst during specimen collection, the blood being tested is not the same as the blood circulating in the patient. It's as different as night and day. Because red blood cells contain 23 times as much potassium as the liquid portion of the blood, when red cells rupture during collection, the specimen being submitted for testing is spiked with potassium. In fact, it's spiked with so much potassium that, if tested and reported, the results can send the physician into a sheer panic, forcing him or her to react with orders that can be ultimately unfavorable to the patient. Or, if the patient's circulating potassium is actually too low, hemolysis can spike the specimen into a normal range and lead to inaction when action is necessary. But it's not just potassium that hemolysis affects. These other tests are affected when hemolyzed specimens are submitted for testing: LDH, AST, ALT, phosphorous, magnesium, ammonia, RBC, hemoglobin and hematocrit. Not only these analytes, but virtually everything that could be tested. That's because hemoglobin is a liquid protein which dilutes the serum or plasma being tested. The greater the hemolysis, the greater the dilution. Suffice it to say hemolysis is just all-around nasty. So how do those who collect specimens prevent the lab from reporting inaccurate results? Check your practices to minimize these seven top causes:
- Avoid line draws---IV devices are notorious for hemolyzing red cells. Unless you're using a device like PIVO, perform a venipuncture instead;
- Avoid vigorous mixing---think of red cells as fragile crystal orbs that fracture with the least amount of disturbance;
- Avoid excessive pulling pressure when using syringes---red cells don't tolerate the excessive turbulence from forcefully withdrawing the plunger of the syringe;
- Don't rim clots---rimming clots to remove fibrin invariably ruptures red cells at the same time;
- Position the needle properly---a needle partially occluded by the vein wall is a needle that hemolyzes red cells;
- Prewarm skin puncture sites---this reduces the need to excessively squeeze the tissue, which hemolyzes red cells;
- Fill tubes fully---an excessive concentration of anticoagulant when tubes are underfilled is hard on fragile red cell membranes.
Using these and other techniques can minimize your potential to hemolyze specimens. Since accurate results begin with the collector, those who draw blood specimens are in the best position to make sure patients are treated according to results that are not delayed or altered because of hemolysis.
The real art of hemolysis is in avoiding it in the first place.
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