Quick Question Results: Bethesda Titers

The results of our latest Quick Question are in with 87 responses..

How does your laboratory measure factor inhibitors?

1. Standard Bethesda assay: 33% (26)
2. Bethesda titer using buffered pH 7.4 pooled normal plasma: 9% (8)
3. Nijmegen Bethesda assay using factor-depelted plasma as diluent: 9% (8)
4. CDC modification of Nimegen Bethesda assay: 0% (0)
5. Bethesda chromogenic assay: 3% (3)
6. We send out to a reference laboratory: 45% (42)

It appears the folks at the CDC (click or tap) have some work to do promoting their modification of the Nijmegen Bethesda assay, which includes heat-treating specimens to destroy residual factor VIII activity prior to measurement, using buffered pH 7.4 pooled normal plasma, diluting the patient specimen in factor-depleted plasmas or albumin, and employing a formula for computation of Nijmegen Bethesda units, all meant to improve assay reliability.