TEG Functional Fibrinogen Assay Useful in Assessing Platelet and Fibrinogen Contributions to Clot Integrity

Research involving a thromboelastography (TEG) functional fibrinogen (FF) assay found this test to be accurate in comparison to the standard von Clauss fibrinogen assay (Shock 2013;39:45–9). The study also found that FF can be performed rapidly with TEG, suggesting this assay can be used to guide rapid diagnosis and appropriate blood component treatment in severely injured trauma patients.

The authors conducted this study because although TEG assays have been widely adopted and are emerging as the standard of care in managing trauma patients, at least some may have a limitation in differentiating between platelet and fibrinogen contribution to clot integrity. In particular, kinetic time and α angle typically are used to assess fibrinogen function, but have not been well-correlated to clinical fibrinogen levels. Advent of a TEG FF assay enables measurement of the fibrinogen that is actively involved in thrombus formation, and comparison of this to overall clot strength. The researchers hypothesized that a TEG FF assay would assess the contribution of fibrinogen and platelets to clot strength in severely injured patients and provide insight to transfusion regimens.

The study involved citrated whole-blood samples from 68 trauma patients and 10 healthy volunteers, the latter to demonstrate the causal role of fibrinogen on clot strength. The authors performed von Clauss, FF, and kaolin TEG assays on the samples from trauma patients, and kaolin and FF TEG assays on samples from the healthy volunteers. The investigators found that FF results strongly correlated with both von Clauss levels, with R2 of 0.87, and clot strength, with R2 of 0.80. The mean fibrinogen contribution to clot strength was 30%; however, there was a direct linear relationship with fibrinogen level and percent fibrinogen contribution to clot strength. The authors concluded that fibrinogen levels should be addressed early in severely injured trauma patients presenting with abnormal clot strengths.

Urinary L-FABP Good Discriminator for Acute Kidney Injury

A meta-analysis of hospital-based cohorts at risk for acute kidney injury (AKI) found that urinary liver-type fatty acid-binding protein (L-FABP) provides good discrimination for diagnosing AKI and predicting both the need for dialysis and in-hospital mortality (Am J Kidney Dis 2013;61:430–9). The authors conducted the analysis because L-FABP is one of several candidate biomarkers that might detect and predict AKI risk earlier than serum creatinine.

The investigators found 23 studies that met their eligibility criteria, of which 13 cohort studies representing 1,684 patients were included in the meta-analysis. The estimated sensitivity and specificity of urinary L-FABP for diagnosing AKI were 74.5% and 77.6% respectively; L-FABP’s sensitivity and specificity in predicting the need for dialysis were 69.1% and 42.7%, respectively, and its sensitivity and specificity for in-hospital mortality were 93.2% and 78.8%, respectively.

The authors noted that while this may have been the first analysis of all published cohort studies of patients at risk for AKI, it was limited by the small number and low quality of these studies, the heterogeneity of the study populations, and variable definitions of AKI and biomarker cutoff values. For these reasons, they called for further large cohort studies across a broad range of clinical settings to assess the diagnostic and prognostic value of urinary L-FABP.