Plasma renin activity is associated with bone mineral density in premenopausal women

Bone mineral density (BMD), plasma renin activity (PRA) and dietary calcium and sodium were evaluated in 47 Caucasian premenopausal women. All subject s were free of any disorder or medications known to affect calcium or bone metabolism. Those subjects with low PRA (< 1.3 ng/ml) had 4.3% lower BMD at the distal radius (p = 0.03). Other skeletal sites appeared to have lower BMD in subjects with low PRA but these differences were not statistically s ignificant. There was a tendency for the low PRA group to have a lower diet ary intake of calcium (p = 0.06) as compared with the normal PRA group (gre ater than or equal to 1.3 and <4.0 ng/ml). Positive correlations were found between calcium intake and PRA (r = 0.26, p = 0.09); and between calcium/s odium intake and distal radial BMD (r = 0.31, p = 0.04), mid radial BMD (r = 0.30, p=0.04), total hip BMD (r = 0.23, p = 0.12) and total body BMD (r = 0.27, p = 0.07). This study provides preliminary evidence that a sodium in take >3400 mg/day, as evidenced by the suppression of PRA, may affect bone mass and the effect may be modified by the level of calcium intake. Additio nal research is needed to replicate our findings with a larger sample size.