American Medical Technologist (AMT) Practice Exam

The preferred specimen type for certain chemistry tests is heparinized plasma. Heparinized plasma is used when the anticoagulant heparin is added to a blood sample, preventing clotting. This allows for the measurement of various chemical constituents in the blood without the interference that can be introduced by clotting factors or cellular components. Heparinized plasma is particularly advantageous for specific tests such as electrolyte analysis and certain hormone assays, as it preserves the integrity of the analytes without the potential for hemolysis or cellular contamination that might occur with whole blood or serum. The heparin does not interfere with most of the chemistry tests, making it a suitable choice for many laboratory assays. In contrast, serum is derived from clotted blood and lacks certain analytes that may be present in heparinized plasma. Whole blood includes all blood components, which may compromise the accuracy of tests designed to measure plasma constituents. Platelet-rich plasma, while useful for some specialized tests, is less commonly used for standard chemistry panels and might not be the ideal specimen type for widely performed chemistry tests.