Toenail concentrations of zinc, selenium and nickel in patients with chronic recurrent warts: A pilot two-group comparative study.

Background: Normal immune functioning requires sufficient levels of trace elements including zinc and selenium, while elements such as nickel can be immunotoxic. Aim: To assess long-term abnormalities in zinc, selenium and nickel levels in patients with chronic recurrent warts. Methods: Toenail samples were taken from 28 patients with chronic recurrent warts and 30 apparently healthy matching controls were analysed. Toenail concentrations of zinc, selenium and nickel were measured using inductively-coupled plasma-optical emission spectroscopy. Results: Selenium levels were significantly higher in patients than in controls (P = 0.03). Levels of trace elements did not correlate with the number or duration of warts. Toenail nickel levels in all subjects were higher than globally reported values. Limitations: A small sample size and the absence of regional reference ranges for concentrations of trace elements in toenails. Conclusion: Zinc does not seem to be involved in the chronicity of warts, and it is unclear if selenium has a protective role against warts. Our finding of high concentrations of nickel in both patients and controls raises concerns about environmental exposure.