Biomedical subjects

Giampaolo Zanetti

Publications and source records attributed to Giampaolo Zanetti.

4 recordsLinked to original sources

PubMed2006

Effect of potential renal acid load of foods on urinary citrate excretion in calcium renal stone formers.

The aim of this study was to investigate the influence of the potential renal acid load (PRAL) of the diet on the urinary risk factors for renal stone formation. The present series comprises 187 consecutive renal calcium stone patients (114 males, 73 females) who were studied in our stone clinic. Each patient was subjected to an investigation including a 24-h dietary record and 24-h urine sample taken over the same period. Nutrients and calories were calculated by means of food composition tables using a computerized procedure. Daily PRAL 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. Sodium, potassium, calcium, magnesium, phosphate, oxalate, urate, citrate, and creatinine levels were measured in the urine. The mean daily PRAL was higher in male than in female patients (24.1+/-24.0 vs 16.1+/-20.1 mEq/day, P=0.000). A significantly (P=0.01) negative correlation (R=-0.18) was found between daily PRAL and daily urinary citrate, but no correlation between PRAL and urinary calcium, oxalate, and urate was shown. Daily urinary calcium (R=0.186, P=0.011) and uric acid (R=0.157, P=0.033) were significantly related to the dietary intake of protein. Daily urinary citrate was significantly related to the intakes of copper (R=0.178, P=0.015), riboflavin (R=0.20, P=0.006), piridoxine (R=0.169, P=0.021) and biotin (R=0.196, P=0.007). The regression analysis by stepwise selection confirmed the significant negative correlation between PRAL and urinary citrate (P=0.002) and the significant positive correlation between riboflavin and urinary citrate (P=0.000). Urinary citrate excretion of renal stone formers (RSFs) is highly dependent from dietary acid load. The computation of the renal acid load is advisable to investigate the role of diet in the pathogenesis of calcium stone disease and it is also a useful tool to evaluate the lithogenic potential of the diet of the individual patient.

Acids↗

PubMed2005

Calcium stone disease: a multiform reality.

In calcium renal stones, calcium oxalate and calcium phosphate in various crystal forms and states of hydration can be identified. Calcium oxalate monohydrate (COM) or whewellite and calcium oxalate dihydrate (COD) or weddellite are the commonest constituents of calcium stones. Calcium oxalate stones may be pure or mixed, usually with calcium phosphate or sometimes with uric acid or ammonium urate. The aim of this study was to compare the clinical and urinary patterns of patients forming calcium stones of different composition according to infrared spectroscopic analysis in order to obtain an insight into their etiology. The stones of 84 consecutive calcium renal stone formers were examined by infrared spectroscopy. In each patient, a blood sample was drawn and analysed for serum biochemistry and a 24-h urine sample was collected and analysed for calcium, phosphate, oxalate, citrate and other electrolytes. We classified 49 patients as calcium oxalate monohydrate (COM) stone formers, 32 as calcium oxalate dihydrate (COD) stone formers and three as apatite stone formers according to the main component of their stones. Patients with COM stones were significantly older than patients with COD stones (P < 0.002). Mean daily urinary calcium and urinary saturation with respect to calcium oxalate were significantly lower in patients with COM than in those with COD stones (P < 0.000). Patients with calcium oxalate stones containing a urate component (< or = 10%) presented with higher saturation (P < 0.012) with respect to uric acid in their urine (and lower with respect to calcium oxalate and calcium phosphate, respectively P < 0.024 and P < 0.003) in comparison with patients without a urate component in the stone. Patients with calcium oxalate stones with a calcium phosphate component (> or = 15%) showed higher (P < 0.0016) urinary saturation levels with respect to calcium phosphate (and lower with respect to uric acid (P < 0.009), compared with patients forming stones without calcium phosphate or with a low calcium phosphate component. Patients with calcium stones mixed with urate had a significantly lower urinary pH (P < 0.002) and urinary calcium (P < 0.000), and patients with calcium phosphate >15%, higher urinary pH (P < 0.004) and urinary calcium (P < 0.000). In conclusion, in the evaluation of the individual stone patient, an accurate analysis of the stone showing its exact composition and the eventual presence of minor components of the stone is mandatory in order to plan the correct prophylactic treatment. Patients with "calcium stones" could require various approaches dependent on the form and hydration of the calcium crystals in their stones, and on the presence of "minor" crystalline components that could have acted as epitaxial factors.

Adult↗

PubMed2004

Cystinuria: definition, epidemiology and clinical aspects.

Cystinuria ia an inheritable autosomal recessive disorder of amino acids transport affecting the epithelial cells of the renal tubules and gastrointestinal tract. It is characterized by abnormal concentrations of cystine and the other dibasic amino acids in the urine, resulting in a risk of renal stone formation because of the low solubility of cystine in urine. According to the recent advances in molecular genetics, two genes have been identified as responsible for this disease (SLC3A1 and SLC7A9), but other unknown genes may be involved in cystinuria. We assessed the presence of cystinuria in 2086 consecutive patients with renal stones by using cyanide-nitroprusside test (Brand's test). According to our experience, this screening test should be performed in all patients at the onset of renal stone disease in order to avoid a delay in the possible diagnosis of cystinuria. In fact cystinuric patients often have mixed calculi composed of substances other than cystine that can disguise the presence of cystininuria that is so diagnosed many years after the onset of the initial symptoms. Patients with positive cyanide-nitroprusside test were further studied for identification of urine amino acids by quantitative ion-exchange chromatography. Pathological cystinuria was confirmed in 39 (1.9%) out of 41 patients with positive Brand test. The mean age of cystine stone patients was 38.1 +/- 15.8 years, whereas the age at stone onset was 21.8 +/- 12.4. Renal stones were recurrent in 85% of cases, while other 6 patients were observed at their first stone. The male to female ratio was 1:0.62. The mean number of stone episodes for patient was 18.5 +/- 35.8 and the mean interval to first recurrence was 4.1 +/- 4.3 years. The recurrence rate 5 years after the first renal stone was 83%. Furthermore we studied 85 members from 24 families of patients with cystine stones. Twenty-four family members excreted excessive amounts of cystine, but only 5 of them (21%) had cystine calculi. Twenty-two patients were treated with 1-1.5 g alpha-mercaptopropionylglycine daily. Treatment reduced stone formation from 0.93 to 0.46 stones/patient/year. Only six patients had side effects of sufficient severity to require withdrawal.

Adult↗

PubMed2002

Urinary patterns of patients with renal stones associated with chronic inflammatory bowel disease.

OBJECTIVE: The aim of this study was to analyze the frequency of renal stone patients with chronic inflammatory bowel disease and their urinary patterns. METHODS: During a 20-year period, 1941 consecutive patients with renal stone disease underwent routine laboratory procedures including a fasting blood sample for chemistry profile and a 24-hour urine collection for analyses of electrolytes. Thorough histories including chronic inflammatory disease or ileal resection were obtained. Patients with inflammatory bowel disease together with a control group comprising 47 idiopathic renal calcium stone formers were submitted to a xylose absorption test for evaluation of intestinal absorption. RESULTS: We observed 10 patients with Crohn's disease, 12 with ulcerative colitis and one patient with ileal bypass for obesity. Six patients underwent ileal resection and 10 patients total colectomy. Urinary oxalate excretion was significantly higher and urinary citrate lower in stone patients with ileal disease (Ox 60 +/- 23, Cit 113 + 7-118 mg/day) than in idiopathic stone formers (Ox 28.2 +/- 11.5, Cit 381 +/- 205) and stone patients with ulcerative colitis (Ox 20.3 +/- 14.8, Cit 369 +/- 247). Urinary volume was significantly lower in patients with ulcerative colitis. A significant inverse correlation (-0.38, p < 0.01) between oxalate urinary excretion and blood xylose level was found 2 hours after ingestion of xylose. No significant reduction of xylose absorption was demonstrated in both normoxaluric and hyperoxaluric idiopathic stone patients. CONCLUSIONS: Crohn's disease and ulcerative colitis are characterized by recurrent inflammatory involvement of different intestinal segments involving distinctive urinary patterns. Malabosorption associated with ileal disease causes increased oxalate absorption by increasing oxalate solubility in the intestinal lumen and permeability of the colonic mucosa; a reduced citrate excretion is associated in relation to mild acidosis due to the loss of bicarbonate in the liquid stool. In ulcerative colitis, especially if an ileostomy is present, urine are scanty and concentrated, and urine pH falls, leading to uric acid or mixed stones. Mild hyperoxaluria of idiopathic renal stone formers is not related to subtle intestinal malabsorption.

Adult↗