Levels of circulating FX and PTX2 are interdependent in human plasma. (A) PTX2 and FX antigen levels were measured in human plasma samples obtained from random donors (n = 71). Spearman’s rank correlation coefficient was calculated to assess the statistical dependence of the 2 values. Dots represent each individual sample. (B) PTX2 and FX antigen levels in patients diagnosed with isolated FX deficiency (blue columns; n = 18) or patients under anti–vitamin K treatment (green columns; n = 35) were compared with random donors. Results are expressed as mean ± SD of 18 to 71 samples per group. ***P < .001, statistical significance in a Mann-Whitney nonparametric unpaired test.