Red blood cell transmembrane oxalate flux in calcium-oxalate nephrolithiasis.
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We have studied the metabolic response to changes in calcium in 15 hypercalciuric essential hypertensives, in 8 normotensive hypercalciuric stone formers and in 11 normotensive healthy subjects matched for age and sex. At variance with hypercalciuric stone formers, at low calcium intake hypercalciuric hypertensives did not appropriately reduce urinary calcium excretion and developed mild hypocalcemia. Furthermore, the PTH response to calcium deprivation was not appropriately enhanced in these patients. The data indicate that different mechanisms prevail in these two forms of hypercalciuria: the renal in essential hypertension and the intestinal in urolithiasis.
We have determined that the organic matrix of calcium oxalate kidney stones contains a glycoprotein inhibitor of calcium oxalate crystal growth (nephrocalcin) that resembles nephrocalcin present in the urine of patients with calcium oxalate stones and differs from nephrocalcin from the urine of normal people. Pulverized calcium oxalate renal stones were extracted with 0.05 M EDTA, pH 8.0; nephrocalcin eluted in five peaks using DEAE-cellulose column chromatography, and each peak was further resolved by Sephacryl S-200 column chromatography. Four of the five DEAE peaks corresponded to those usually found in nephrocalcin from urine; the fifth eluted at a lower ionic strength than any found in urine. Amino acid compositions and surface properties of nephrocalcins isolated from kidney stones closely resembled those of nephrocalcins isolated from urine of stone-forming patients: they differed from normal in lacking gamma-carboxyglutamic acid residues, and in forming air-water interfacial films that were less stable than those formed by nephrocalcin from normal urine.
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Our purpose here is to test the hypothesis that Randall's plaques, calcium phosphate deposits in kidneys of patients with calcium renal stones, arise in unique anatomical regions of the kidney, their formation conditioned by specific stone-forming pathophysiologies. To test this hypothesis, we performed intraoperative biopsies of plaques in kidneys of idiopathic-calcium-stone formers and patients with stones due to obesity-related bypass procedures and obtained papillary specimens from non-stone formers after nephrectomy. Plaque originates in the basement membranes of the thin loops of Henle and spreads from there through the interstitium to beneath the urothelium. Patients who have undergone bypass surgery do not produce such plaque but instead form intratubular hydroxyapatite crystals in collecting ducts. Non-stone formers also do not form plaque. Plaque is specific to certain kinds of stone-forming patients and is initiated specifically in thin-limb basement membranes by mechanisms that remain to be elucidated.
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BACKGROUND: To determine factors influencing the clearance of fragments after extra-corporeal shock wave lithotripsy (ESWL) for lower pole calyceal (LPC) stones. METHODS: In the period between July 1998 and Oct 2001, 100 patients with isolated lower polar calyceal calculi or= 14 years, were included in the study. Intravenous urograms (IVU) were reviewed to define the LPC anatomy (width of the infundibulum and pelvicalyceal angle). Study end points i.e. stone free status; number of shock waves used and number of sessions were correlated with variables like LPC anatomy, body mass index and stone size. RESULTS: At three months follow up the clearance for stone size 90 degrees ) had stone clearance of 94 and 100% respectively. For the infundibular width of < 4 mm, the stone clearance was 93% were as for > 4 mm, it was 100%. For body mass index (BMI) less than and > 30 kg/m2, the stone clearance was 92 and 95% respectively. CONCLUSIONS: There is a trend towards more ESWL sessions and shock wave requirement in patients with acute pelvi-calyceal angle and narrow infundibulum but it is not statistically significant. Size (<or= 20 mm) and BMI has no relation with stone clearance. With modern lithotripter, stones up to 20 mm could primarily be treated by ESWL, irrespective of an un-favorable lower polar calyceal anatomy and body habitus.
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