Assayed Information and Courses from MediaLab, Inc.

The activated partial thromboplastin time (APTT) is a screening test that helps to assess the functionality of both the intrinsic and common pathways. The effectiveness and presence of all the coagulation factors are assayed by this diagnostic test with the exception of factors VII and XIII. The results of the activated partial thromboplastin time are used in conjunction with other diagnostic tests, as well as the clinical picture of the patient, to determine hemostatic abnormalities which may be present. In addition to being an integral part of the coagulation disorder assessment process, the APTT is used to determine therapeutic effectiveness of heparin administration. Activated partial thromboplastin time results are presented to the clinician in seconds- the actual time elapsed until a clot was detected using the laboratory's instrument/reagent system.

Commercially prepared controls come in either assayed or unassayed forms. Assayed controls are tested by multiple methods before sale, and are sold with the results of the tests. Assayed controls: are more expensive than unassayed controls are used to evaluate accuracy and precision avoid laboratory errors in determining control values may only be suitable for specific methods or conditionsWhile the manufacturer's control values can be used to some extent to measure accuracy, the best measure of accuracy is certified reference material.Unassayed controls are not tested by the manufacturer before they are sold. The control values for these materials must be determined by the individual laboratory. Unassayed controls: are less expensive than assayed controls are used to evaluate precision only avoid manufacturer error in determining control values control values are customized to the laboratory's own methods and conditionsA final note: although commercially available control materials are screened for hepatitis antigens and HIV antibodies, control materials should still be handled with precautions, since they contain biological materials and could contain infectious agents.