Activated partial thromboplastin time and minor coagulopathies.

Area of Science:

• Hematology
• Clinical Chemistry
• Diagnostic Testing

Background:

• The activated partial thromboplastin time (APTT) is a crucial laboratory test for evaluating the intrinsic pathway of coagulation.
• Accurate detection of mild coagulation factor deficiencies is essential for diagnosing bleeding disorders and managing anticoagulant therapy.

Purpose of the Study:

• To compare the sensitivity of five commercial APTT test systems in detecting minor coagulation defects.
• To evaluate the performance of different reagents (ellagic acid, kaolin, silica, celite) and the kaolin partial thromboplastin time (KPTT) method.

Main Methods:

• Comparison of five commercially available APTT reagents with the KPTT method.
• Testing of plasma samples with known deficiencies in factors XII, VIII, IX, XI, and II, as well as Fletcher factor and Fitzgerald trait.
• Assessment of the impact of heparin on plasma samples.

Main Results:

• All tested APTT systems detected severe factor VIII, IX, and XI deficiencies, as well as homozygous factor XII, Fletcher factor, and Fitzgerald trait deficiencies.
• Reagent E (celite) successfully detected all 19 minor coagulation deficiencies.
• Reagent A (ellagic acid) failed to detect eight deficiencies, while other reagents showed varying degrees of detection failure.
• Heparin's effect was less effectively detected by Reagent A compared to other systems.

Conclusions:

• Significant variability exists among commercial APTT test systems regarding their ability to detect minor coagulation abnormalities.
• The choice of APTT reagent can impact diagnostic accuracy for specific factor deficiencies.
• Reagent E demonstrated superior sensitivity in detecting a broad range of coagulation defects compared to other tested systems.