The investigation of a prolonged APTT with specific clotting factor assays is unnecessary if an APTT with Actin FS is normal

Abstract

This review has demonstrated that no significant coagulation factor deficiency would be left undiagnosed if the protocol was followed. This would have considerably reduced the cost and time spent performing these assays.

Validation of the Sysmex CS5100 coagulation analyzer and comparison to the Stago STA‐R analyzer for routine coagulation parameters

“…The reagents for APTT (Dade Actin FS) and PT (Dade innovin) used on the CS5100 showed a higher sensitivity toward factor deficiencies compared with the reagents used on the STA‐R Evolution instrument. The factor sensitivity was comparable with data from the literature where the same APTT reagent was used . Ideally, reagents should have factor sensitivities between 30 and 45% .…”

“…For APTT, the higher sensitivity toward factor deficiencies may lead to prolonged APTT's in the presence of only mildly reduced factor concentrations or even normal concentrations. These prolonged APTT's should be interpreted with care and may trigger the need for (unnecessary) specific factor assays to be performed . On the other hand, in FXI deficient patients, the FXI concentration is not correlated with the bleeding phenotype and a reagent with higher factor sensitivity is useful to diagnose these patients .…”

Laboratory and Quality Control of Assays

“…When individuals with prolonged APTT arising out of routine screening are investigated, FXI deficiency was approximately five times more common than either FVIII of FIX deficiency [17] though this finding is likely to be dependent on the reagent used for screening.…”

Sequential thrombosis and bleeding in a woman with a prolonged activated partial thromboplastin time

“…Urine and blood cultures were negative. Since 1988 in Airedale the possibility of a bleeding disorder was tested by comparing the clotting times of two aPTT reagents, currently Synthesil (IL) as the reagent sensitive to factor inhibitors and deficiencies and Actin FS (Dade) as the reagent insensitive to factor inhibitors and deficiencies but sensitive to factor XII deficiency [2]. Unbeknown to the laboratory personnel the same comparison can be used to detect a lupus anticoagulant [3].…”