Table 1.
Molecular weight and anti-factor Xa and anti-factor IIa activities of heparin and commonly used low molecular weight heparins (LMWH).a
Figure 1.
Boxplots of the four aPTT methods’ results for enoxaparin and tinzaparin in three different concentrations.
When comparing the contiguous groups with the same aPTT-method but different concentrations of LMWH, a significant difference in aPTT was found in all cases. Statistical significances between classes are shown in S1 File.
Figure 2.
A comparison of enoxaparin and tinzaparin’s relative effects on aPTT.
Bland-Altman plot showing that the aPTT’s induced by tinzaparin ranged from on average 49% more than enoxaparin (when measured using the PTT-Automat reagent) to 66% more than enoxaparin (when measured using the MRX931 reagent (FOR: free oscillation rheometry).
Figure 3.
Relationship between measured anti-FXa and the concentration of low molecular weight heparin (LMWH).
There is a strong linear correlation between anti-FXa results and the concentration of LMWH (dosed in anti-FXa units per ml). For enoxaparin and tinzaparin the correlation coefficients Rs are 0.97 and 0.96 respectively.
Figure 4.
Correlations between aPTT and anti-FXa at varying concentrations of enoxaparin and tinzaparin, using various reagents.
Anti-FXa activity reflects the concentration of LMWH and the aPTT correlated well to this measure. The correlation for Hemochron Jr is slightly weaker than for the other reagents (see Table 2).
Table 2.
Explanatory to Fig. 4: Correlation and regression between aPTT and Anti-FXa for enoxaparin and tinzaparin.
Figure 5.
Thrombin generation at increasing concentrations of LMWHa, measured using the TGA RC reagent.
Thrombin generation is inhibited in a negative exponential manner by increasing doses of LMWH. There is a significant difference between Endogenous Thrombin Potential (ETP) at all contiguous concentrations and between ETP for the two reagents at each individual concentration (P<<0.05). aLow Molecular Weight Heparin. bETP: Endogenous Thrombin Potential.
Figure 6.
Relationship between aPTT measured using various reagents, and the logarithm of thrombin generation.
See Table 3 for correlation factors and regression lines. There is a negative linear relationship between aPTT and log10(ETP). Tinzaparin results in prolonged aPTT results compared to enoxaparin in the whole blood analyses (FOR and Hemochron Jr) at any given level of thrombin generation.
Table 3.
Explanatory to Fig. 6.
Figure 7.
Relationship between anti-FXa activity and thrombin generation.
Anti-FXa activity is strongly negatively correlated to the logarithm of ETP (Endogenous Thrombin Potential): Rs for enoxaparin and tinzaparin are −0.93 and −0.94 respectively. Anti-FXa activity is more prolonged by enoxaparin than tinzaparin at any given level of thrombin generation.