Calcium and phosphorus concentrations and the calcium/phosphorus ratio in trabecular bone from the femoral neck of healthy humans as determined by neutron activation analysis.

The Ca and P concentrations as well as the Ca/P ratio were estimated in intact trabecular bone samples from the femoral neck of healthy humans, 34 women and 44 men, aged from 15 to 55 years, using instrumental neutron activation analysis. The mean values (M+/-SD) for the investigated parameters (on a dry-weight basis) were: 12.1+/-3.0%, 5.94+/-1.71%, 2.07+/-0.25 and 10.9+/-2.5%, 5.30+/-1.23%, 2.07+/-0.22 for females and males, respectively. A statistically significant (p</=0.05) decrease of Ca concentration with age was found only for males while the P concentration and the Ca/P ratio were not affected by age. No statistically significant sex-related differences were observed in any of the parameters. The mean values for Ca, P and the Ca/P ratio lay close to the median of the very wide range of published data. The individual variation for the Ca/P ratio in trabecular bone from the healthy human femoral neck was lower than those for Ca and P separately. This suggests that the specificity of the Ca/P ratio is better than that of Ca and P concentrations and may be more reliable for the diagnosis of bone disorders.