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

Tunç Özen,1 Mehmet Salih Gürel,1 Ozan Erdem,1 Derviş Özçelik2 ,†Nural Pastacı Özsobacı,2 Şahabettin Selek,3 Fatmanur Köktaşoğlu3 1Department of Dermatology, Istanbul Medeniyet University, İstanbul, Türkiye; 2Department of Biophysics, Cerrahpaşa Faculty of Medicine, İstanbul, Türkiye; 3Department of Biochemistry, Bezmialem Vakıf University, İstanbul, Türkiye†Derviş Özçelik passed away on October 15, 2025Correspondence: Tunç Özen, Department of Dermatology, Istanbul Medeniyet University, İstanbul, Türkiye, Tel +905389515911, Email [email protected]: 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.Plain Language Summary: Psoriasis can affect the nails and impair appearance and daily functioning. To monitor nail changes, practical and non-invasive biomarkers are needed. In this study, we compared two groups of people with psoriasis: those with nail problems and those without. Small nail clippings were collected from each participant. We measured very small amounts of certain minerals (trace elements, such as zinc and selenium) and building blocks of proteins (amino acids) in these samples.We found that some minerals and amino acids were lower in patients with nail problems, while histidine was higher. These values also tracked with how severe the nail findings were. This suggests that analyzing nail clippings could provide a laboratory-based, non-invasive way to follow nail disease in psoriasis. Larger studies are needed to confirm these results before they can be used routinely in clinics.Keywords: psoriasis, nail involvement, trace elements, amino acids, NAPSI, LC-MS/MS, ICP-OES