Among the excluded patients, the most common situation was a “low probability of PE” V/Q scan interpretation and low clinical suspicion for PE. Another shortcoming of this study is a limited experience in applying the FPA assay designed for plasma to urine testing. One investigation suggests that urine contains significant amount of carboxyterminally degraded FPA, which may be undetected by assays that contain antibody directed mostly against the carboxyterminal. This reduced sensitivity may cause spuriously low values, and some patients with elevated plasma FPA may have normal urine FPA. The assay used in this study identified all patients who had PE; therefore, there who was no clinical evidence that the study assay suffers from reduced sensitivity. In addition, it is known that antibodies that cross-react with canine FPA are directed against the carboxyterminal portion of the peptide. The antibody used in our assay has no significant cross-reactivity with canine FPA, thus providing a strong evidence that it is directed against the amino terminal. buy flovent inhaler
In conclusion, this pilot study suggests that in patients with suspected PE: (1) uFPA may be useful for excluding the diagnosis of PE; and (2) the combination of uFPA and V/Q scans may exclude more patients than either test alone. Because the number of patients is small, the results are considered to be preliminary, and further studies are needed to confirm our findings in a larger and more diverse population of patients suspected of PE.