Hemolyzed blood occurs when red blood cells (RBCs) rupture, releasing their internal contents into the surrounding fluid. This process, called hemolysis, can happen within the body or, more commonly, during blood sample collection and handling. When RBCs break open, they release substances like hemoglobin, which interferes with laboratory tests. This often leads to inaccurate results, posing a challenge in medical diagnostics and patient care.
Understanding Hemolysis
Red blood cells transport oxygen and carbon dioxide. Their delicate membrane, when damaged, causes them to burst and release internal components. Hemoglobin, the protein giving blood its red color, is the most prominent substance released during hemolysis.
When a blood sample hemolyzes, the normally clear, yellowish liquid portion (plasma or serum) takes on a pink or reddish tint from the released hemoglobin. Both plasma and serum are susceptible to hemolysis, which compromises the accuracy of laboratory analyses.
Common Causes of Hemolysis
Hemolysis can occur outside the body (pre-analytical) or within the body (in-vivo). Pre-analytical hemolysis is common in laboratory settings, often stemming from improper blood collection or handling. Causes include using a needle that is too small, excessive suction, or vigorously shaking the collection tube. Incorrect tube filling, prolonged tourniquet application, extreme temperatures during transport, or delayed processing also contribute to red blood cell rupture.
In-vivo hemolysis occurs inside the body due to medical conditions. This indicates an underlying health problem. Examples include autoimmune disorders, infections like malaria, or inherited blood disorders such as sickle cell anemia. Severe burns, incompatible blood transfusions, or mechanical damage from artificial heart valves can also destroy red blood cells.
How Hemolysis Affects Blood Test Results
The rupture of red blood cells during hemolysis releases intracellular substances into the plasma or serum, significantly altering laboratory test results. Many analytes are present in much higher concentrations inside red blood cells than in the surrounding fluid. For example, potassium levels inside red blood cells are significantly higher than in plasma. Even minor hemolysis can cause a falsely elevated potassium reading, known as pseudohyperkalemia.
Other substances like lactate dehydrogenase (LDH), aspartate aminotransferase (AST), and magnesium are also more concentrated within red blood cells, leading to falsely high measurements. Conversely, hemolysis can lead to falsely decreased levels of certain analytes, such as bilirubin, by interfering with testing methods. These inaccurate results can lead to misdiagnosis or inappropriate treatment, making blood sample integrity important for patient care.
Minimizing Hemolysis During Blood Collection
Preventing hemolysis during blood collection and handling is important for accurate lab results. Healthcare professionals follow guidelines to minimize red blood cell damage. Using an appropriate needle size and performing venipuncture with a gentle technique reduces physical trauma. Avoiding excessive pulling pressure with a syringe and gently inverting tubes, rather than shaking, helps preserve sample integrity.
Proper handling extends to the post-collection phase. This includes correct tube filling, minimizing tourniquet application time to less than one minute, and allowing alcohol to dry completely. Maintaining appropriate temperatures during transport and promptly processing samples also prevents further cellular breakdown. Adequate patient hydration before blood draws can facilitate easier venipuncture, reducing the risk of hemolysis.
When Hemolysis Indicates a Health Issue
When hemolysis occurs within the body, it is termed in-vivo hemolysis. This indicates an underlying medical condition where red blood cells are prematurely destroyed, a process that can lead to hemolytic anemia. The body continually produces new red blood cells, but in hemolytic anemia, destruction outpaces production.
People experiencing in-vivo hemolysis might exhibit symptoms such as fatigue, pale skin, dizziness, and dark urine due to hemoglobin release. Jaundice, a yellowing of the skin or eyes, can also occur because of increased bilirubin levels. If in-vivo hemolysis is suspected, further medical investigation identifies and addresses the specific cause, which could range from inherited disorders to autoimmune conditions or infections.