When a repeat PT is ordered for a patient with a high hematocrit, which adjustment may need to be made?

In the context of performing a prothrombin time (PT) test for a patient with a high hematocrit, adjusting the citrate concentration is essential. High hematocrit levels indicate that there is a higher concentration of red blood cells in the blood sample. When performing coagulation tests like the PT, citrate is used as an anticoagulant to prevent clotting in the sample. The standard citrate concentration is based on a normal range of blood components. If the hematocrit is significantly elevated, the volume of plasma relative to the cellular components is reduced, which can lead to inaccurate results if the citrate concentration remains the same.

By adjusting the citrate concentration, you ensure that there is sufficient anticoagulant to effectively bind the calcium present in the plasma, allowing for a more accurate assessment of the coagulation factors present without interference from an altered blood composition. This adjustment compensates for the varying proportions of red blood cells and can improve the reliability of the PT results, making it crucial in such cases.