Test Catalog

Test ID: CH8B    
Chromogenic Factor VIII Inhibitor Bethesda Titer, Plasma

Method Description Describes how the test is performed and provides a method-specific reference

In the Bethesda procedure, patient plasma is heat inactivated (HI) at 56 degrees C for 30 minutes. Next using the HI patient plasma, serial dilutions are prepared and mixed in equal volumes with normal pooled plasma. The mixture is incubated 2 hours at 37 degrees C. At the end of the incubation, chromogenic factor VIII (CH8) activity is measured and compared to a control performed at the same time. The difference between the CH8 activity of the patient's incubation mixture and that of the control is used to calculate the titer. The residual CH8 activity is converted to Bethesda units: 50% residual CH8 is equal to 1 Bethesda unit. Assays using the same basic principle as the Bethesda assay are used to quantitate the inhibitors of the other coagulation factors.(Kasper CK, Aldedort LM, Counts RB, et al: A more uniform measurement of factor VIII inhibitors. Thromb Diath Haemorrh 1975;34:869-872; Miller C: Laboratory testing for factor VIII and IX inhibitors in haemophilia: A Review. Haemophilia 2018;00:1-12)

PDF Report Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.

Monday through Friday; Varies

Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.

2 days

Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

7 days

Performing Laboratory Location Indicates the location of the laboratory that performs the test