Nail Amino Acid and Trace Element Profiles and Their Association with Clinical Severity in Nail Psoriasis

Abstract

Background: Nail involvement is common in psoriasis, yet objective and non-invasive biomarkers of nail disease activity are limited. The biochemical composition of the nail plate may reflect local pathophysiological changes and could provide measurable indicators of disease severity. Objective: To compare the nail biochemical composition between psoriatic patients with and without nail involvement, and to examine its associations with nail severity. Methods: In this case-control study, nail clippings from adults with psoriasis were analyzed for trace elements (Cr, Cu, Fe, Mn, Mg, Se, Zn) by ICP-OES and for amino acids by LC-MS/MS. Group comparisons and correlation analyses with the Nail Psoriasis Severity Index (NAPSI) were conducted, and multivariable logistic regression identified independent predictors of nail involvement. Results: Fifty-seven patients were included (30 with nail involvement; 27 without). Compared with patients without nail involvement, those with nail psoriasis showed significantly lower nail levels of several trace elements and amino acids, whereas histidine was higher (all p < 0.05). NAPSI correlated negatively with selenium, zinc, glycine, and proline, and positively with histidine. In multivariable analysis, lower nail selenium and asparagine and higher histidine independently predicted nail involvement. Conclusion: Psoriatic nail dystrophy is associated with a distinct biochemical profile in the nail plate. Selected trace elements and amino acids correlate with clinical severity and may represent potential biochemical indicators of nail disease activity. Prospective studies are warranted to validate these findings.