Analytical Control Systems, Inc.

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Analytical Control Systems, Inc.

Platelet Testing

SPAT™ and Spectra™ APCT An Introduction

Two new tests help the laboratorian evaluate human platelet function.

For the last several years, four basic tests have been used by clinical laboratory professionals to screen patient samples for possible coagulation problems. The prothrombin time is used to identify extrinsic coagulation problems. The Activated Partial Thromboplastin Time (APTT) is used to evaluate the intrinsic coagulation system. Platelet counts and bleeding time tests are used to check platelets.

The Prothrombin Time and the Activated Partial Thromboplastin Time have proven to be reliable and accurate tests for the extrinsic and intrinsic coagulation systems. Prolonged test results indicate potential at-risk bleeding situations in patients and have correlated well with clinical conditions.

However, platelet counts and bleeding times, while providing useful information on occasion, have not provided the clinical investigator with effective screening tools to evaluate the kinetics of platelet function. The results of bleeding times are highly variable and can be misleading. Laboratory professionals have known for a long time that bleeding times suffer from these problems, but no effective alternative test was available. Platelet counts, although helpful in extreme ranges as an indicator of potential problems, again do not demonstrate whether platelets are functional.

Analytical Control Systems, Inc. has developed two new coagulation screening tests that enhance the clinical investigator's ability to evaluate platelet function. The assessment of both the ability of platelets to aggregate¹ and to express platelet factor 3² is now a reality.

The patented Slide Platelet Aggregation Test (SPAT™) requires just 0.1 ml of platelet rich plasma and 0.1 ml of reagent and is a quick, inexpensive, easy, qualitative, three minute slide test that determines if platelets are capable of aggregating. The patented Spectra™ Activated Plasma Clotting Time (APCT) test is performed in the same manner and on the same equipment as an APTT. To run the test, 0.1 ml of plasma (either platelet rich plasma or platelet poor plasma) and 0.1 ml of reagent are incubated at 37^o C for three to five minutes. At the end of the incubation period, 0.1 ml of 0.02 M calcium chloride is added and the time of clot formation is noted. Since the Spectra™ APCT reagent contains no platelet factor 3 substitute, the formation of the clot is supported by the expression of platelet factor 3 from the platelets in the sample being tested.

Analytical Control Systems, Inc., with the introduction of these new platelet evaluation tests, has initiated a new era in coagulation testing. The implications for emergency platelet testing, platelet screening, drug monitoring and clinical patient diagnosis abound.