[Urinary excretion of sodium and magnesium in idiopathic hypercalciuria]

We have studied urinary sodium and magnesium excretion in 30 normal subjects (15 women and 15 men, mean age 43 +/- 14 years, mean weight 74 +/- 18 Kg) and in 60 hypercalciuric stone-forming patients, 30 with renal hypercalciuria (HR) (15 women and 15 men, mean age 39 +/- 10 years, mean weight 71 +/- 16 Kg) and 30 with absorptive hypercalciuria (HA), (15 women and 15 men, mean age 41 +/- 13 years, mean weight 69 +/- 12 Kg). The diagnosis of hypercalciuria and the classification in HA and HR was made with our ambulatory study protocol. Hypercalciuria was defined by a daily calcium excretion above 300 mg (men) or 220 mg (women), and patients with fasting calcium to creatinine ratio, and calcium per 100 ml of glomerular filtrate average value above 0.11 were considered to have HR. Control subjects and hypercalciuric patients were maintained on a diet containing 1200 mg Ca, 800 mg P, 200 mg Mg and 100 mmol Na per day for a 7-day period. Two 24-hour urine samples were collected on days 6 and 7 of this diet. On the morning of day 8, following a 12-hour fast, 300 ml of distilled water was drunk and a 2-hour urine sample was collected. A blood sample was taken halfway this time. In all blood and urine samples, calcium, magnesium, sodium, phosphorus and creatinine were quantified. Creatinine clearance and calcium, sodium and magnesium per 100 ml of glomerular filtrate were calculated from these determinations.(ABSTRACT TRUNCATED AT 250 WORDS)