ENPP2 and Pruritus: Serum ATX activity correlates with pruritus intensity and response to treatment in patients with cholestatic pruritus, but not with this symptom when it is associated with other etiologies.4, 12, 13, 14, 15, 16, 17 Carrion et al. (2018) found in patients with cholestasis and pruritus that ATX activity is significantly higher than in those with cholestasis without pruritus, and ATX levels correlate with the severity of this symptom.