Fasting urinary sodium/creatinine in relation to calcium/creatinine and hydroxyproline/creatinine in a general population of women.

The relationships between urinary sodium excretion and bone loss and bone turnover were studied by looking at sodium/creatinine (Na/creat) values in relation to: (a) calcium/creatinine (Ca/creat); and (b) hydroxyproline/creatinine (HP/creat) values in fasting urines obtained from 574 women over 16 years of age participating in a health survey. Na/creat was positively correlated with Ca/creat (r=0.567, p less than 0.001) and with HP/creat (r=0.341, p less than 0.001). Both young and old women showed these relationships. However, postmenopausal women had higher Na/creat, Ca/creat and HP/creat values than premenopausal women. It seems that subjects with a high sodium excretion show a higher net bone loss and a higher bone turnover than subjects with low sodium excretion. The results suggest that salt intake should be considered when evaluating bone loss and bone turnover from fasting urinary Ca/creat and HP/creat measurements.