Table 1.

Characteristics of population under study

Variable	Values
N (men/women)	393 (317/76)
Age, yr	45±10
Body mass index, kg/m2	25.8±3
History of kidney stones, n (%)	33 (9)
Hypercalciuric subjects, n (%)	102 (26)
eGFR, ml/min per 1.73 m2	94±18
Serum creatinine, mg/dl	0.9±0.2
Serum sodium, mmol/L	142±2
Serum calcium, mg/dl	9.2±0.4
Urinary sodium, mmol/24 h	146±67
Urinary calcium, mg/24 h	207±115
Basal systolic BP, mm Hg	142±15
Basal diastolic BP, mm Hg	91±11
Basal mean BP, mm Hg	108±11
N (men/women)	370 (301/69)
Urinary sodium before NaCl infusion from −120 to 0 min, mmol/2 h	15.4±13.6
Urinary sodium during NaCl infusion from 0 to 120 min, mmol/2 h	52.4±29.9
Urinary sodium after NaCl infusion from 120 to 240 min, mmol/2 h	51.5±29.0
Urinary calcium before NaCl infusion from −120 to 0 min, mg/2 h	21.7±18.8
Urinary calcium during NaCl infusion from 0 to 120 min, mg/2 h	28.9±19.4
Urinary calcium after NaCl infusion from 120 to 240 min, mg/2 h	18.4±15.2
Mean BP increment at the end of NaCl infusion, mm Hg	2.3±6.6
Mean BP increment at the end of test, mm Hg	1.9±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.