Calcium and magnesium in human toenails do not reflect bone mineral density.

Nail mineral composition is influenced by several physiological and pathological processes. Potentially, nails could be used to monitor alterations in the level of incorporation of specific elements produced by nutritional abnormalities, disease states or chronic exposure to toxic agents. The purpose of this study was to investigate whether the calcium and magnesium content in nail clippings, as measured by instrumental neutron activation analysis (INAA), correlates with bone mineral density (BMD), as measured by quantitative microdensitometry (QMD), and therefore could be interesting as a screening instrument for osteoporosis. The study involved 220 women, who participated in a breast cancer screening project (the DOM-project) in Utrecht, the Netherlands. The correlations found between Ca and Mg measurements and bone mineral densities were very low (correlation coefficients ranging from 0.03 to 0.18). It is concluded that Ca and Mg measurements in nail clippings by INAA cannot be used for screening purposes in the prevention of osteoporosis.