Conventional Rapid Latex Agglutination in Estimation of von Willebrand Factor: Method Revisited and Potential Clinical Applications

Table 7

Correlation of result interpretations by latex agglutination test and immunoturbidimetric assay.

Qualitative latex agglutination test (LAT score)	Semiquantitative latex agglutination test (titre)	VWF : Ag levels by immunoturbidimetric assay (%)
1+	1 : 2	<20
2+	1 : 4, 1 : 8	20–50
3+	1 : 16, 1 : 32	50–150
4+	≥64	>150

The proposed interpretation guide: normal level of VWF : Ag is indicated by LAT scores of 2+ and 3+ or titres from 1 : 8 to 1 : 32. Abnormal low VWF : Ag is indicated by LAT scores of 0, 1+, and 2+ or titres of 1 : 2 and 1 : 4. Abnormal high VWF : Ag is indicated by LAT score of 4+ or titres of ≥64.
LAT: latex agglutination test; VWF : Ag: von Willebrand factor antigen.