[Relation of fingernail mineral concentrations to bone mineral density in elderly Japanese women]

Metacarpal bone mineral density, and concentrations of calcium (Ca), iron (Fe), magnesium (Mg), zinc (Zn) and phosphorus (P) in fingernails were measured in 30 elderly women. Significant correlation between bone mineral density and body weight was seen, and higher values of bone mineral density were observed in those subjects walking daily without the aid of a cane or assistance. Among the 5 minerals in fingernails, a high positive correlation was found between Ca and P concentrations. Concentration of Zn in fingernails was significantly but negatively correlated with bone mineral density (r = -0.399), and a significant positive correlation of Ca/Zn ratio of fingernails was observed with bone mineral density (r = 0.421). The content of Zn in nails may be affected by alterations in bone Zn status and a potential application of nail Zn level or Ca/Zn ratio as an indicator of senile osteoporosis is suggested.