Effect of potential renal acid load of foods on calcium metabolism of renal calcium stone formers.

OBJECTIVES: Diet has been proposed as a causative factor of hypercalciuria in patients with calcium stones. The aim of this study was to investigate the influence of diet on calcium metabolism of renal stone formers. METHODS: Thirty-five renal calcium stone formers were entered in this study. A 2-day recall of dietary intake was obtained from each subject. The food records were coded and computer analyzed for total energy, protein, fat, carbohydrate, sodium, potassium, calcium, magnesium, phosphate, oxalate, vitamin C and fiber. Daily potential renal acid load (PRAL) of the diet was calculated considering the mineral and protein composition of foods, the mean intestinal absorption rate for each nutrient and the metabolism of sulfur-containing amino acids. A fasting blood sample was drawn and a 24-hour urine collection were obtained for analyses of calcium, phosphate and creatinine. Serum osteocalcin was also analyzed. A fasting 2-hour urine sample was collected in the morning for hydroxyproline, pyridinium cross-links and creatinine. RESULTS: The mean daily dietary PRAL of renal stone formers was 22.4 +/- 15.7 (range 4.2-65.8) mEq/day. Regression analysis demonstrated that urinary calcium excretion is dependent on daily protein intake and dietary PRAL, whereas the urinary pyridinium cross-links/creatinine ratio is inversely dependent on daily calcium intake. The urinary pyridinium cross-links/creatinine ratio was significantly lower in patients on a low calcium diet (< 600 mg/day) than in other patients (19.5 +/- 7.8 vs. 27.3 +/- 7.5 nM/mM, p = 0.008). No significant difference was observed between the 2 groups for daily urinary calcium (254 +/- 109 vs. 258 +/- 140 mg/day), serum osteocalcin (8.2 +/- 3.3 vs. 6.2 +/- 2.4 ng/ml) and urinary hydroxyproline/creatinine (14.1 +/- 7.4 vs. 10.3 +/- 4 mg/g). CONCLUSIONS: The urinary calcium excretion of renal stone formers seems to be dependent on dietary acid load rather than dietary calcium intake. In patients consuming an acidifying diet a restriction of calcium intake could increase bone resorption leading to a progressive bone loss.

Evaluation of urinary level of NMP22 as a diagnostic marker for stage pTa-pT1 bladder cancer: comparison with urinary cytology and BTA test.

BACKGROUND: In the present study we compared the clinical value of two new specific tests for transitional cell carcinoma, urinary nuclear matrix protein (NMP22) levels and bladder tumor antigen (BTA) test, with that of urinary cytology in the follow-up of patients with superficial bladder cancer. MATERIALS AND METHODS: Hundred and five bladder cancer patients were recruited: 30 stage pTa and 45 stage pT1 (group A), and 30 with a history of bladder cancer but no recurrence at the time of the study (group B). Urine samples were collected before any instrumental manipulation of the genitourinary tract. All patients were negative for urinary tract infections at conventional urine analysis. RESULTS: NMP22 at a cutoff value of 6 U/ml showed a sensitivity of 83.3% in pTa cases and 97.7% in pT1 cases, with a false-positive rate of 23.3%. The BTA test was positive in 26.6% of patients with cancer stage pTa and in 66.6% of pT1 stage, with 30% false-positives in the non-neoplastic group. Urinary cytology, performed on three consecutive samples, was positive in 20% of patients with cancer stage pTa and in 64.4% of pT1 stage and did not show any false-positive cases. Stratifying the neoplastic patients according to lesion grade, NMP22 (at a cutoff value of 6 U/ml) was positive in 86.2% of G1, 97.2% of G2 and 90% of G3. BTA was positive in 37.9, 52.7 and 70% of G1, G2 and G3, respectively, while urinary cytology was positive in 37.9, 44.4 and 80%.

[Orthotopic ileal neobladder: urodynamic and metabolic aspects. Our experience]. / Neovescica ileale ortotopica: aspetti urodinamici e metabolici. Nostra esperienza.

We subjected to a functional and metabolic evaluation (urodynamic examination + cystography) 10 patients underwent to radical cystectomy with a ileal orthotopic reservoir (VIP) for bladder cancer. At the moment patients have a minimum 3-years follow-up and they are out of disease. The medium capacity of the reservoir is about 447 ml, with a low pressure flow, a medium pressure of ureteral closing of 62.5 cm of H2O. At the cystography neither ureteral reflux nor post miction residuum have been proved. All the patients are continent, with the exception of one patient suffering from episodes of nocturnal enuresis. The metabolic evaluation hasn't proved substantial changes except the presence of hypocitraturia in the only patient in metabolic acidosis. In conclusion the ileal orthotopic reservoir showed a good long-term functionality without considerable complication of metabolism.

Clinical observations on 2086 patients with upper urinary tract stone.

The present series comprises 2086 consecutive patients who were studied in a stone clinic during a period of 15 years. Each patient was subjected to a comprehensive protocol including a fully biochemical investigation. Calcium stones were by far the commonest accounting for 61% of cases; infection, uric acid/calcium oxalate and cystine stones accounted respectively for 24%, 8%, 5% and 2%. Nephrolithiasis was more prevalent in males with the male to female ratio 1:0.76, on the other hand infection stones were more frequent in females with the male to female ratio 1:1.6. The peak age incidence of renal calcium stones occurred in the third to fifth decades, although about 3.4% reported onset of disease in the first and second decades of life. The onset of cystine stones was always in the first and second decades, while uric acid stones affected older patients. Renal stones were recurrent in about 50% of cases. In a retrospective analysis it was found the interval to first recurrence to be less than 5 years in about half patients. The cystine and uric acid groups had the highest rate of recurrence. In patients with calcium stones a definite metabolic or mechanical cause for their stones was found respectively in 8.2% and 10.1%. Particularly primary hyperparathyroidism was revealed in 2.8%. A metabolic defect could be found in 54% of the patients with idiopathic calcium stones. In these patients with idiopathic calcium stones the prevalence rate of hypercalciuria was 33%. In patients with uric acid stones and with mixed uric acid/calcium oxalate stones a definite metabolic cause for their stones was found respectively in 9.5% and 4.1% whereas an underlying disease of the urinary tract was diagnosed respectively in 8.5% and 6.2%. In patients with struvite stones the incidence of persistent infection was 46% (Proteus 18%). In this group the presence of an underlying disease of the urinary tract was diagnosed in 18.8% whereas a definite metabolic disease was demonstrated in 8.5%, a urinary risk factor for metabolic stone disease in 42% and a previous episode of metabolic stone disease in 33%.