SHORT-TERM EFFECTS OF DIETARY-SODIUM INTAKE ON BONE METABOLISM IN POSTMENOPAUSAL WOMEN MEASURED USING URINARY DEOXYPYRIDINOLINE EXCRETION

The influence of Na load on bone metabolism was investigated in postme nopausal women using urinary deoxypyridinoline (DPD) as a marker of bo ne resorption, In across-over study, fourteen postmenopausal women wer e divided into two groups of seven. A fixed diet providing 816 mg Ca/d with either 60 or 170 mmol Na/d was consumed. At the end of an 8 d pe riod the groups switched diets for a further 8 d period. Urine was col lected daily for the last 4 d of each period. There was no significant difference in DPD excretion between high-Na and low-Na diets (129 nmo l/d v. 132 nmol/d; P = 0.18). There was, however, a significant relati onship (P = 0.02) between the changes in DPD excretion and urinary Ca. Plasma Mg fell from 0.83 to 0.81 mmol/l on the high Na intake (P < 0. 001), but there was no significant effect on plasma Ca or intact parat hyroid hormone levels. It is concluded that varying dietary Na intake may affect Ca and Mg metabolism, but we were unable to demonstrate an effect on bone resorption at the levels of intake used.