Table 1.

Characteristics of population under study

VariableValues
N (men/women)393 (317/76)
 Age, yr45±10
 Body mass index, kg/m225.8±3
 History of kidney stones, n (%)33 (9)
 Hypercalciuric subjects, n (%)102 (26)
 eGFR, ml/min per 1.73 m294±18
 Serum creatinine, mg/dl0.9±0.2
 Serum sodium, mmol/L142±2
 Serum calcium, mg/dl9.2±0.4
 Urinary sodium, mmol/24 h146±67
 Urinary calcium, mg/24 h207±115
 Basal systolic BP, mm Hg142±15
 Basal diastolic BP, mm Hg91±11
 Basal mean BP, mm Hg108±11
N (men/women)370 (301/69)
 Urinary sodium before NaCl infusion from −120 to 0 min, mmol/2 h15.4±13.6
 Urinary sodium during NaCl infusion from 0 to 120 min, mmol/2 h52.4±29.9
 Urinary sodium after NaCl infusion from 120 to 240 min, mmol/2 h51.5±29.0
 Urinary calcium before NaCl infusion from −120 to 0 min, mg/2 h21.7±18.8
 Urinary calcium during NaCl infusion from 0 to 120 min, mg/2 h28.9±19.4
 Urinary calcium after NaCl infusion from 120 to 240 min, mg/2 h18.4±15.2
 Mean BP increment at the end of NaCl infusion, mm Hg2.3±6.6
 Mean BP increment at the end of test, mm Hg1.9±6.9
  • Calcium excretion was measured in 24-hour urine in 393 patients and 2-hour urine collections during the NaCl infusion test in 370 patients. The NaCl infusion test lasted 6 hours and consisted of three 2-h periods during which urine was collected: an equilibration period followed by an infusion period (in which patients were infused with 2 L of 0.9% NaCl solution) and a recovery period after the infusion.