Calcium, phosphorus, calcium-phosphorus ratio in rib bone of healthy humans.

Calcium and phosphorus concentrations as well as the Ca/P ratio were estimated in intact rib bone samples from healthy humans, 37 women and 45 men, aged 15-55 yr. For Ca and P concentration measurements, instrumental neutron activation analysis was used. The mean values (mean +/- SD) for the investigated parameters were 19.3 +/- 4.5% of dry bone weight, 8.42 +/- 2.14% of dry bone weight, and a ratio of 2.33 +/- 0.34, respectively. Statistically significant differences for the above parameters were not observed to be related either to age or sex. The mean values for Ca, P, and the Ca/P ratio were within a very wide range of published data and close to their medians. The individual variation for the Ca/P ratio in rib bone from healthy humans was lower than those for Ca and P taken separately. An indication is that the specificity of the Ca/P ratio improves upon that for Ca and P concentrations and may be more reliable in the diagnosis of bone disorders.