Aim: There are no studies regarding comparative analysis of serum biomarkers of oxidative stress in patients with psoriasis (PsO) and atopic dermatitis (AD). We aimed to compare the serum redox homeostasis parameters in patients with PsO vs. AD in an attempt to find the sensitive and specific oxidative stress biomarker that could best reflect the existence of one of these disease entities. Methods: Forty patients with PsO and forty patients with AD were consecutively included in this cross-sectional study. Parameters of redox homeostasis, i.e., pro-oxidants [malondialdehyde (MDA) and advanced oxidation protein products (AOPP)] and antioxidants [catalase (CAT) and superoxide dismutase (SOD)] were determined. Results: There was no difference in oxidative stress biomarkers between the PsO and AD group, except for higher CAT activity in the AD group (p < 0.001). Among all examined redox homeostasis biomarkers, ROC analysis showed that only CAT exhibited good diagnostic accuracy (AUC = 0.719) in the discrimination of patients with PsO vs. AD, with 0.436 U/L as the cut-off value of CAT activity. Conclusions: The CAT exhibited good diagnostic accuracy in the discrimination of patients with AD from those with PsO. The obtained results could suggest the importance of the use of antioxidants as a potential therapeutic strategy in the treatment of these two skin inflammatory diseases.
