A Comparison of Effects Induced on Urinary Calcium by Thiazides and Different Doses of Salt in the Diet: 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 21 of Nutrison (R) Low Sodium (500 mg sodium/day) daily for two days. Then, 5 g of NaCl were added every two days (<< 5 >>, << 10 >> and << 15 >>), administering 50 mg (H50) and 100 mg (H100) of Higroton (R) 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/24 h): 210.3 +/- 87.6 (<< B >>); 42.7 +/- 20.4 (<< 5 >>); 135.5 +/- 50.6 (<< 10 >>); 225.5 +/- 56.7 (<< 15 >>). Urinary calcium (mg/24 h): 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 (R), 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 +/- 14.9 g/day with a positive correlation found between sodium and calcium urine output with daily intakes of 11.25 and 16.25 g of salt. With the usual intake, for each gram of salt, urinary calcium increased by 5.46 mg/24 h and with 100 mg of Higroton (R) it decreased by 50.7 mg/24 h. These data could be useful for the management of patients with excretory hypercalciuria or hypoparathyroidism. (C) 2018 Sociedad Espanola de Nefrologia. Published by Elsevier Espana, S.L.U.