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Excerpt
The objective of this study was to investigate the effect of dietary advice on actual urinary composition and supersaturation in male patients with idiopathic calcium urolithiasis. Forty-seven male patients with idiopathic calcium renal stone formation (ICSF) were enrolled in the study. Mean age was 44±1.3 years (range 28-68 years). Patients reported an average 5.3±0.6 stones (range 1-18 stones). Forty-five out of 47 patients were recurrent stone formers.
Two or three 24-h baseline urine samples were obtained after a minimum of 2 months from passage of the last stone with patients on a free diet. Dietary advice was given by a dietician over one or two 30- to 45-min sessions. Dietary advice was aimed at increasing urine output to more than 2000 ml/day, limit meat protein intake to 1.0 g/kg body weight, decrease salt consumption to less than 200 mmol/day and to maintain calcium intake from dairy products at 800 mg/day. Follow-up 24-h urine samples were collected after an average 146±10 days (range 37-300 days). An increase in urine volume and a decrease in urea concentration in urine×urine volume (UUrea×V) product was considered ‘good compliance’, improvement in one of the two parameters only and worsening in both parameters were considered as ‘moderate’ or ‘poor compliance’, respectively. Daily protein consumption and net gastrointestinal absorption of alkali were calculated. Twenty-four-hour urine collections from 68 healthy individuals on a free diet with no personal or family history of urolithiasis were used as controls. Twenty-four-hour collections were performed in 3-l plastic bottles with 10 g of boric acid as preservative agent. Urine samples were analysed for calcium, phosphate, magnesium, sodium, potassium, chloride, uric acid, urea and creatinine. Urine pH was measured. Oxalate, sulfate and citrate were measured. Relative supersaturations (RSs) of calcium oxalate, apatite, brushite and uric acid in 24-h urine collections were calculated.
Twenty nine of the 47 patients with ICSF were normocalciuric (NCSF) and 18 were hypercalciuric (HCSF). HCSF had a larger urine volumes and a higher RScalcium oxalate than NCSF (Ucalcium×V and Uoxalate ×V). The same applied for RSapatite, and RSuric acid, RScalcium oxalate and RSbrushite were higher in ICSF patients than in control individuals. Overall, no change in urinary supersaturation was found following dietary advice in ICSF patients, RScalcium oxalate values remained elevated also compared with the control group, whereas a significant decrease in RSuric acid was found. Good compliance with dietary advice was achieved in nine out of 47 ICSF patients only (19%), 33 patients out of 47 (70%) were considered moderate compliers, and five patients (11%) were poor compliers. Good compliance resulted in urine volume increase by 46.2±11.2% with decrease in Uurea×V by 16.8±4.1%. RScalcium oxalate consequently fell by 25.6±12.1% and RSurea decreased by 49.2±11.9%. No change in RSbrushite and RSapatite was observed in this group. In patients with moderate compliance, no change in urine volume and Uurea×V was found but RScalcium oxalate increased by 9.6±7.5%. In the poor compliance group, urine volume decreased by 16.6±6.2%, with consequent increase in Uurea×V, RScalcium oxalate and RSurea.
Dietary advice was aimed at correcting individual dietary and urinary risk factors, so that ICSF patients with less than 2000 ml/day urine volume were encouraged to increase fluid intake, whereas patients with urine volume greater than 2000 ml/day were encouraged to reduce protein and salt intake.
