What is hemoconcentration caused by during a blood draw?

Hemoconcentration occurs when there is an increased concentration of cellular components in the blood due to the loss of plasma volume. This phenomenon is typically caused by prolonged tourniquet application. When a tourniquet is applied for an extended period of time, it restricts blood flow and leads to a pooling of blood in the veins, which can result in the dilution of plasma and an increase in the relative concentration of red blood cells, white blood cells, and platelets.

This is significant because hemoconcentration can lead to falsely elevated laboratory test results, as the increased cellular components can affect various blood assays, including those for electrolytes, proteins, and other analytes. Therefore, it's crucial for phlebotomists to limit the duration of tourniquet application to help ensure accurate test results and patient safety.