A comparison of induced effects on urinary calcium by thiazides and different dietary salt doses: Implications in clinical practice.

INTRODUCTION

Both dietary restriction of sodium chloride (NaCl) and treatment with thiazides have been used in hypercalciuric patients.

OBJECTIVES

To calculate regular salt intake and investigate the correlation between natriuresis and urinary calcium with usual diet (B) and after changing the amount of NaCl intake and administration of thiazides.

MATERIAL AND METHODS

Nineteen healthy young individuals had their diet replaced by 2l of Nutrison Low Sodium (500mg sodium/day) daily for two days. Then, 5g of NaCl were added every two days («5», «10» and «15»), administering 50mg (H50) and 100mg (H100) of Higroton on the last two days. Blood sodium, plasma renin activity (PRA) and aldosterone were determined in venous blood samples, as were urinary sodium and calcium.

STATISTICAL ANALYSIS

Wilcoxon t-test and the Pearson linear correlation were calculated.

RESULTS

Urinary Na (mEq/24h): 210.3±87.6 («B»); 42.7±20.4 («5»); 135.5±50.6 («10»); 225.5±56.7 («15»). Urinary calcium (mg/24h): 207.8±93.6 («B»); 172.8±63.1 («5»); 206.2±87.7 («10»); 227.4±84.1 («15»). A positive correlation was observed between natriuresis and urinary calcium in «10» (r=0.47) and «15» (r=0.67). After Higroton, natriuresis: 232.3±50.7; 377±4 (H50); 341.1±68.4 (H100); Ca in urine: 209.8±57.4; 213.2±67.6 (H50); 159.1±52.2 (H100).

CONCLUSIONS

Salt intake in the population studied was estimated to be 14.9±4.9g/day with a positive correlation found between sodium and calcium urine output with daily intakes of 11.25 and 16.25g of salt. With the usual intake, for each gram of salt, urinary calcium increased by 5.46 mg/24 h and with 100mg of Higroton it decreased by 50.7mg/24h. These data could be useful for the management of patients with excretory hypercalciuria or hypoparathyroidism.