Trace element concentrations in human fingernails

Abstract

The concentrations of calcium, sodium, zinc, magnesium, potassium, copper and iron in fingernails of 199 male and 220 female subjects aged 1 to 83 years were determined by atomic absorption spectroscopy. To facilitate comparison, the relative concentration was calculated by normalizing the concentration of each element to that of untreated nails (100%). Of the seven elements in nails washed with nonionic detergent, the concentration of Na (101%) was the highest, followed by Zn (97%), Cu (88%), Fe (87%), Ca (79%), K (78%) and Mg (63%). Trace element concentrations in fingernails show large variability and usually have a skewed frequency distribution pattern, which calls for logarithmic data transformation rather than an arithmetric mean, this giving a more suitable estimate of each element. The concentrations of Ca, Mg and Fe in fingernails were significantly higher in the males than in the females when the subject pool was broken down by sex. Both sex groups over the age of 60 years exhibited significant decreases of Ca and increases of Na or K.The correlations of log Na-log K (female: r=0.857, male: r=0.793) and Ca-Mg (female: r=0.892, male: r=0.838) were the strongest obtained in this study. There were significantly positive correlations between husband and wife, father or mother and son, and mother and daughter for several elements in fingernails. These correlations may be explained by the similar eating habits and life styles of such couples.To date there is very little information on human fingernail trace element concentrations. The results of this study can be used as basic data for trace element study in human fingernails.