OXT and progressive pseudorheumatoid arthropathy of childhood: Findings of 14 studies (4, 13, 15–26) included five hypotheses regarding the relationship between hormones and the presence of PPD (Table 1): (H-I) changes in dopamine receptors, (H-II) increase in cortisol, (H-III) changes in estrogen levels, (H-IV) presence of thyroid dysfunction, and (H-V) decrease in oxytocin.