Determination of calcium, phosphorus, and the calcium/phosphorus ratio in cortical bone from the human femoral neck by neutron activation analysis.

Concentrations of Ca and P as well as the Ca/P ratio were estimated in intact cortical bone samples from the femoral neck of healthy humans, 33 women and 45 men, aged from 15 to 55 yr using instrumental neutron activation analysis. Mean values (M +/- SD) for the investigated parameters (on dry weight basis) were: 23.0 +/- 3.9%, 10.7 +/- 2.4% and 2.17 +/- 0.31, respectively. No statistically significant differences of the above parameters were observed related either to age or sex. The mean values for Ca, P and Ca/P ratio were within a very wide range of published data and close to their median. The individual variation for the Ca/P ratio in cortical bone from the healthy human femoral neck was lower than those for Ca and P separately. This means that specificity of Ca/P ratio is better than those of Ca and P concentrations are and may be more reliable for diagnosis of bone disorders.