"Flag H" on lab results is a common abbreviation used to indicate that a specimen has been hemolyzed. This means that the red blood cells in the sample have been broken down, potentially affecting the accuracy of the results.
Why Hemolysis Occurs
Hemolysis can occur during the blood draw or during the handling and processing of the blood sample. Here are some common causes:
- Improper venipuncture technique: If the needle is inserted too deeply or if the vein is not properly stabilized, the red blood cells can be damaged.
- Vigorous shaking or squeezing of the blood tube: This can cause the red blood cells to rupture.
- Using a too-small needle: This can cause the red blood cells to be damaged as they pass through the needle.
- Prolonged tourniquet application: This can cause blood to back up in the vein, leading to hemolysis.
- Delay in processing the sample: If the blood sample is not processed quickly enough, the red blood cells can begin to break down.
Impact of Hemolysis on Lab Results
Hemolysis can affect the results of many lab tests, particularly those that measure:
- Electrolytes: Hemolysis can release potassium, phosphate, and other electrolytes from the red blood cells, leading to falsely elevated results.
- Enzymes: Certain enzymes, such as lactate dehydrogenase (LDH), are present in high concentrations in red blood cells. Hemolysis can release these enzymes into the serum, leading to falsely elevated results.
- Hemoglobin: Hemolysis can lead to falsely elevated hemoglobin levels.
What to Do if a Sample is Flagged as Hemolyzed
If a sample is flagged as hemolyzed, the lab may need to repeat the test. This is because the results may not be accurate.
How to Prevent Hemolysis
Here are some tips to help prevent hemolysis:
- Use proper venipuncture technique.
- Avoid vigorous shaking or squeezing of the blood tube.
- Use the appropriate needle size.
- Apply the tourniquet for no longer than 1 minute.
- Process the blood sample promptly.
