[Changes in phospho-calcium metabolic factors in function of the rate of bone turnover. Epidemiologic study of osteoporosis (part 2)].

BACKGROUND

The recent development of highly accurate and precise osseous mass quantitative evaluation methodology, permits the conduction, in the sphere of osteoporosis, of epidemiologic investigations no longer limited solely to fracture complications, but also based on the definition of osseous mass. Fractures being only complications, possible but not certain, of the advanced stages of the disease, the studies based on their incidence allow one to underestimate the global entity of prevalence and incidence, besides building only a partially useful reference in view of primary and secondary prevention.

METHODS

The main points of our study are the following: 1) evaluation of the incidence of the primary risk factors for osteoporosis as they appear in the literature, on the bone mass values of examined subjects, utilizing static mineralometric data as a reference standard; 2) study of biohumoral data relative to phospho-calcium metabolism and to sexual function, to show the possibility of their use as early identifying markers of subjects at risk; reference values represented by dynamic mineralometric data. The principal conclusions that emerged in the course of the study are the following.

RESULTS

In relation to the use of phospho-calcium metabolic biohumoral and hormonal variables, as a predictive function on the variations of bone turnover, the variables; osteocalcin, alkaline phosphatase, alkaline phosphatase bone isoenzyme, hydroxyprolinuria/ creatininuria, have resulted significantly different in the comparison between high and low turnover subjects. The degree of quantitative correlation of such variables with the entity of percentage decrement of bone mass has been modest. The overall value of R-square of the predictive model, besides the variables mentioned the value of bone mass at 1 degree control visit, was 0.38 (osteocalcin: 0.27; osteocalcin+hydroxyprolinuria/ creatininuria: 0.33; preceding variables+bone mass at 1st control: 0.36; preceding variables+alkaline phosphatase: 0.37; preceding variables+alkaline phosphatase bone isoenzyme: 0.38).

CONCLUSIONS

The single value osteocalcin may furnish indications on the future variations of bone turnover and consequently on the early identification of the subjects at risk for osteoporosis at high turnover; the addition of the other variables indicated in our predictive model allows an increase of the possibilities of individualizing of these subjects.