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At least 19 recordsLinked to original sources
PubMed1991

Metabolism of pyridoxine in mild metabolic hyperoxaluria and primary hyperoxaluria (type 1).

Plasma pyridoxine metabolites in plasma and 4-pyridoxic acid excretions in urine were measured in normal subjects, in 7 patients with type-1 hyperoxaluria and in 8 patients with mild metabolic hyperoxaluria, while receiving various doses of pyridoxine. Compliance with ingestion of pyridoxine was verified by measuring urinary 4-pyridoxic acid. In the normal subjects the maximum level of pyridoxal phosphate was obtained after only 10 mg/day of pyridoxine. The patients were divided into nonresponders, good responders and poor responders to pyridoxine according to the fall in urinary oxalate and glycollate excretions. In patients taking pyridoxine, the plasma pyridoxal phosphate levels were as for normal subjects in primary hyperoxaluria, lower than for normal subjects in mild metabolic hyperoxaluria (p less than 0.01), and in the latter group lower in partial responders than in good responders (p = 0.04). Hence in mild metabolic hyperoxaluria there may be difficulty in converting pyridoxine to pyridoxal phosphate.

Chromatography, High Pressure Liquid↗
PubMed1990

Plasma oxalate and creatinine and oxalate/creatinine clearance ratios in normal subjects and in primary hyperoxaluria. Evidence for renal hyperoxaluria.

Plasma oxalate and creatinine were measured repeatedly in healthy individuals and in 12 patients with type 1 primary hyperoxaluria unresponsive to pyridoxine. The mean ratios were 0.025 (SD 0.006) and 0.120 (SD 0.048), respectively. One patient repeatedly had normal plasma oxalate despite markedly raised urinary oxalate and it seems unlikely that this excess oxalate could have come from the liver. Oxalate/creatinine clearance ratios in the normal group had an overall mean of 0.59 (SD 0.27) in 24 h urine collections and 0.741 (SD 0.297) in repeated short clearance periods. Both renal tubular absorption and secretion of oxalate apparently occurred on different days, but this did not depend upon urinary flow rate. Oxalate/creatinine clearance ratios in type 1 primary hyperoxaluria had a mean of 2.88 (SD 3.11). The raised oxalate/creatinine clearance ratios in the patients were not correlated with either plasma oxalate or creatinine. A few patients showed much higher clearance ratios and in some were sufficiently high to indicate that oxalate was generated and secreted in the kidneys.

Creatinine↗
PubMed1991

Combined liver-kidney and isolated liver transplantations for primary hyperoxaluria type 1: the European experience. The European Study Group on Transplantation in Hyperoxaluria Type 1.

The data provided by 14 European centres concerning 22 combined liver-kidney and two isolated liver grafts performed in primary hyperoxaluria type 1 (PH1) were discussed at a workshop which drew the following main conclusions: 1. In end-stage renal failure due to PH1 1-year kidney graft survival rate is far better after combined liver-kidney transplantation than after kidney transplantation alone. This may be due to enhanced renal graft tolerance induced by the simultaneously grafted liver, in addition to the reduced risk of oxalate-induced damage to the kidney graft because the oxalate overproduction has been corrected. 2. Prolonged dialysis using conventional regimes gives rise to extensive systemic oxalosis, especially oxalate osteopathy, which leads to long-lasting excretion of large amounts of oxalate even after oxalate synthesis has been normalised by liver-kidney transplantation, with the risk of jeopardising the success of the kidney graft. In addition, oxalate arteriopathy may endanger the recipient's life. 3. Patients whose GFR is in the range of 25-60 ml/min per 1.73 m2 should be followed up closely, with sequential assessments based on the rate of loss of overall renal function and the plasma and urine oxalate values. An isolated liver transplantation should be considered once the disease has been shown to be following an aggressive course. If this strategy is not followed, planning for an elective liver-kidney graft should begin when GFR decreases to about 25 ml/min per 1.73 m2 and the operation should be as soon as possible. 4. As orthotopic liver transplantation involves the removal of the recipient's biochemically defective but otherwise normal liver, the diagnosis of PH1 should be unequivocally established in every case by the measurement of alanine: glyoxylate aminotransferase enzyme activity in a preoperative liver biopsy.

Adolescent↗
PubMed1991

Hyperoxaluria in patients with recurrent calcium oxalate calculi: dietary and other risk factors.

The presence of mild hyperoxaluria in recurrent calcium oxalate stone formers is controversial. The aim of this study was to identify recurrent stone formers with mild hyperoxaluria and to classify them further by assessing their response to a low oxalate diet. In addition, the prevalence of other risk factors for stone formation in this group of patients was investigated. A total of 207 consecutive patients with recurrent renal calculi were screened and 40 (19%) were found to have mild hyperoxaluria. Of these, 18 (45%) responded to dietary oxalate restriction by normalising their urinary oxalate. The remaining 22 patients were classified as having idiopathic hyperoxaluria and were subdivided into those in whom urinary oxalate excretion was consistently elevated in all specimens measured and those in whom the elevation was intermittent in nature. Dietary oxalate restriction had a partially beneficial effect in lowering oxalate excretion in the patients with persistent hyperoxaluria. No difference in urinary oxalate excretion was found after dietary restriction in the patients with intermittent hyperoxaluria. Other risk factors, including dietary, absorptive and renal hypercalciuria and hypocitraturia, were documented, the prevalence of which (65%) was not significantly different from that (62.5%) found in 40 age- and sex-matched calcium stone formers without hyperoxaluria. The prevalence of hyperuricosuria was significantly greater in patients with hyperoxaluria when compared with stone controls. Further studies are required to elucidate the underlying mechanisms of hyperoxaluria in recurrent stone formers.

Calcium↗
PubMed1986

The determination of oxalate in haemodialysate and plasma: a means to detect and study 'hyperoxaluria' in haemodialysed patients.

In order to find out whether hyperoxaluria can be demonstrated in patients on chronic (twice a week) haemodialysis, a group of 13 patients was investigated. These included one patient with proven primary hyperoxaluria, one suspected of having this disease and 11 patients in whom no information was available as to their oxalate metabolism. Oxalate concentrations in haemodialysate fractions and blood samples, taken before and after dialysis, were determined. The patient with primary hyperoxaluria had a plasma oxalate concentration before dialysis above 100 mumol/l and after dialysis above 25 mumol/l, while the oxalate concentration in haemodialysate at the start of dialysis was above 25 mumol/l and at the end above 10 mumol/l. The patient suspected of hyperoxaluria had similar values. Of the remaining 11 patients, one was shown to exhibit a transient hyperoxaluria, but the others showed a normal oxalate metabolism. A plasma oxalate/creatinine concentration ratio exceeding 0.1, and the calculated total quantity of oxalate removed by dialysis exceeding 2 mmol, also enabled a diagnosis of hyperoxaluria to be made. Hyperoxaluria can still be demonstrated in patients, who because of renal failure are subjected to haemodialysis. Measurements of oxalate in haemodialysate and plasma are valuable in cases where kidney transplantations are considered, especially when the particular patient exhibits hyperoxaluria.

Adolescent↗
PubMed1987

Oxalate dynamics in chronic renal failure. Comparison with normal subjects and patients with primary hyperoxaluria.

In order to separate the effect of oxalate retention in primary hyperoxaluria with renal failure from that of excessive oxalate synthesis and to determine the optimum time for renal transplantation in primary hyperoxaluria, we have studied a series of patients with different degrees of renal failure due to other causes. The results were compared with those obtained in studies on 8 patients with primary hyperoxaluria at different levels of residual overall renal function. In the patients with renal failure unrelated to primary hyperoxaluria, oxalate retention increases rapidly when the glomerular filtration rate (GFR) decreases below about 20 ml X min-1. These results suggest that the reduced renal excretory contribution to oxalate accumulation in primary hyperoxaluria would be expected to be particularly important in this range of GFR. In primary hyperoxaluria, oxalate retention occurs when GFR is only a little below the reference range and measures to remove oxalate from the body should be considered when the GFR falls below 40 ml X min-1 X 1.73 m-2, with a view to their introduction when the GFR is in the range 20-25 ml X min-1 X 1.73 m-2.

Carbon Radioisotopes↗
PubMed1989

Perspectives in the assessment and management of patients with primary hyperoxaluria type I.

In normal adults the urinary excretion of oxalate rarely exceeds 0.5 mmol/24 hours-1 despite dietary and seasonal fluctuations of intake and absorption. Hyperoxaluria may be encountered in a number of disease states because of increased absorption of dietary oxalate or derangements of metabolism (Table 1). More unusually, hyperoxaluria may arise from one of three inborn errors of metabolism, i.e., the primary hyperoxalurias. The most common, primary hyperoxaluria type I (PHI), is recessively inherited; it will be discussed in detail in this paper. Primary hyperoxaluria type II, caused by a deficiency of D-glycerate dehydrogenase (EC 1.1.1.29), has a similar clinical pattern of disease, but has been described in only a very few families. More recently, another idiopathic form of hyperoxaluria has been defined (type III). It is likely that this form results from a primary defect in oxalate absorption in the absence of any morphologically or functionally definable intestinal disease; a satisfactory response to dietary restriction of oxalate, along with the use of thiazide diuretics, has been described.

Humans↗
PubMed1992

Plasma and urine glycolate assays for differentiating the hyperoxaluria syndromes.

To differentiate hyperoxaluria syndromes we measured plasma and urine glycolate by a novel high performance liquid chromatographic procedure. Mean glycolate level was 7.9 +/- 2.4 mumol./l. in plasma and 422 +/- 137 mumol./24 hours in urine from 19 control subjects. Renal clearance was about 50% the glomerular filtration rate irrespective of the underlying disease. There was close correlation between glycolate and oxalate in plasma. Plasma glycolate was normal in all but 8 patients who had primary hyperoxaluria 1. Plasma assay detected the disease more efficiently than urine assay. Pyridoxine decreased oxalate biosynthesis in 2 of the 4 patients treated with it and glycolate assay confirmed this behavior. Glycolate excretion was significantly high in 3 of 8 patients of primary hyperoxaluria 1 patients. Idiopathic stone formers had mild increases in glycolate excretion but this was not related with oxalate excretion. Glycolate levels were normal in 5 patients with enteric hyperoxaluria. We conclude that glycolate assay is essential for identifying patients with primary hyperoxaluria 1 and may represent a valuable tool for differentiating hyperoxaluria.

Adolescent↗
PubMed1991

Diet and hyperoxaluria in the syndrome of idiopathic calcium oxalate urolithiasis.

Hyperoxaluria is an important risk factor in patients who form calcium oxalate stones within the urinary tract. It occurs in patients with primary hyperoxaluria, enteric hyperoxaluria, and the syndrome of idiopathic calcium oxalate urolithiasis. In the latter condition, the specific causes of the hyperoxaluria are not well defined. Diet and the availability of calcium and oxalate from the diet within the intestine are important factors in the hyperoxaluria that is present in some of these patients with idiopathic calcium oxalate urolithiasis. Other abnormalities in endogenous metabolism or transport of oxalate may play a role in the hyperoxaluria in some of these patients.

Calcium↗
PubMed1986

Absorptive hyperoxaluria: a new clinical entity--successful treatment with hydrochlorothiazide.

This report describes studies performed over an 11 year period in a 13 year old girl with hyperoxaluria and calcium oxalate nephrolithiasis who did not have primary hyperoxaluria or any of the recognized causes of secondary hyperoxaluria. The patient also had increased urinary excretion of calcium and magnesium and hyperabsorption of dietary calcium and magnesium. It is suggested that the hyperoxaluria resulted from hyperabsorption of dietary oxalate secondary to hyperabsorption of dietary calcium. Hyperabsorption of dietary magnesium and increased urinary magnesium excretion have not previously been reported in this context. Stone formation ceased and urinary oxalate excretion gradually fell to normal during long term thiazide therapy but hyperoxaluria recurred when orthophosphate therapy was substituted for the hydrochlorothiazide. This is the first report of normalization of urine oxalate excretion during thiazide therapy in a patient with frank hyperoxaluria.

Adolescent↗
PubMed1977

Importance of the colon in enteric hyperoxaluria.

To investigate the role of the colon in increased oxalate absorption, we measured urinary oxalate and fecal fat excretion in 26 patients with gastrointestinal disease. Eight patients with steatorrhea of various causes (Crohn's disease [two], chronic pancreatitis [four], jejunoileal bypass [one] and extrahepatic biliary obstruction [one]) had hyperoxaluria (greater than 45 mg per 24 hours). All these patients had intact colons. In contrast, none of five patients with ileostomies and steatorrhea secondary to ileal resection had hyperoxaluria. Absorption of 14C-oxalate was increased in three patients with steatorrhea and intact colons but not in three patients with steatorrhea and an ileostomy. Thus, the colon is both the site of and required for increased oxalate absorption in enteric hyperoxaluria. The lack of a direct relation between fecal fat excretion and urinary oxalate excretion in the patients with hyperoxaluria and steatorrhea suggests that steatorrhea, although important, is not the only determinant in the pathogenesis of hyperoxaluria.

Celiac Disease↗
PubMed1985

Response to a physiologic dose of pyridoxine in type I primary hyperoxaluria.

We measured urinary oxalate and glycolate excretion before and during pyridoxine administration (2 to 200 mg per day) in four patients with primary hyperoxaluria. In two patients with type I primary hyperoxaluria, urinary oxalate and glycolate excretion fell markedly in response to a physiologic dose of pyridoxine of 2 mg per day and became completely normal when the dose was increased to 25 mg per day. In the other two patients, who had a different type of primary hyperoxaluria (normal urinary glycolate excretion), there was no response to 2 mg of pyridoxine per day. In one of these patients, doses of 25 and 50 mg per day were also ineffective, but a moderate reduction in oxalate excretion took place with 200 mg per day; in the other patient there was a moderate reduction in oxalate excretion with 25 mg of pyridoxine per day. Our findings suggest that the degree of hyperoxaluria in this disorder may be only slight or moderate if the patient has been ingesting a pyridoxine-rich diet or multivitamin tablets containing small amounts of pyridoxine. Our results also suggest that smaller doses of pyridoxine than those heretofore employed should be tried in patients with primary hyperoxaluria.

Child↗
PubMed1990

Ocular findings in primary hyperoxaluria.

Primary hyperoxaluria (primary oxalosis) is a rare autosomal recessive inborn error of glyoxylate metabolism that causes widespread calcium oxalate crystal deposition in diverse tissues. Because others have reported only occasional ocular involvement, we reviewed the ophthalmologic findings in our 24 patients with primary hyperoxaluria to document its funduscopic variability and to determine its visual prognosis and its possible systemic significance. Eight (30%) of our 24 patients with primary hyperoxaluria exhibited a bilaterally symmetrical retinopathy. The abnormalities were predominantly confined to the posterior pole and ranged from many small (100- to 200-microns) subretinal black ringlets to single large (2- to 3-disc diameter) geographic lesions. In 3 of the 8 patients with oxalate retinopathy, diffuse optic disc pallor was evident. Five patients with both normal-appearing optic discs and oxalate retinopathy had relatively good visual acuities. The maculopathy of primary hyperoxaluria caused mild visual impairment while optic nerve dysfunction associated with this disease appeared to be much visually debilitating. Also, the presence of oxalate maculopathy was associated with a more severe systemic course for the disease.

Acute Kidney Injury↗
PubMed1988

Further studies on the activity and subcellular distribution of alanine:glyoxylate aminotransferase in the livers of patients with primary hyperoxaluria type 1.

1. The activity of alanine:glyoxylate aminotransferase (AGT; EC 2.6.1.44) has been measured in the unfractionated livers of 20 patients with primary hyperoxaluria type 1 (PH1), three patients with other forms of primary hyperoxaluria and one PH1 heterozygote. The subcellular distribution of AGT activity was examined in four of the PH1 livers and in the liver of the PH1 heterozygote. 2. The mean AGT activity in the unfractionated PH1 livers was 12.6% of the mean control value. The activities of other aminotransferases and the peroxisomal marker enzymes were normal. When corrected for cross-over from glutamate:glyoxylate aminotransferase (GGT; EC 2.6.1.4), the mean AGT activity in the PH1 livers was reduced to 3.3% of the control values. 3. The livers from a patient with primary hyperoxaluria type 2 (D-glycerate dehydrogenase deficiency) and one with an undefined form of primary hyperoxaluria (possibly oxalate hyperabsorption) had normal AGT levels. The livers of a very mild PH1-type variant and a PH1 heterozygote had intermediate levels of AGT activity. 4. Subcellular fractionation of four PH1 livers by sucrose gradient isopycnic centrifugation demonstrated a complete absence of peroxisomal AGT activity. The subcellular distribution of the residual AGT activity was very similar to that of GGT activity (i.e. mainly cytosolic with a small amount mitochondrial). There were no alterations in the subcellular distributions of any of the peroxisomal marker enzymes. The subcellular distribution of AGT activity in the PH1 heterozygote liver was similar to that of the control (i.e. mainly peroxisomal).

Adolescent↗
PubMed1991

Glycolate determination detects type I primary hyperoxaluria in dialysis patients.

The detection of type I primary hyperoxaluria is based on the finding of exceedingly high oxalate excretion which is associated with increased glycolate excretion. The differential diagnosis of this disease may become a difficult task once end-stage renal disease (ESRD) and anuria have supervened. The various procedures thus far proposed to obviate this circumstance are complex, inaccurate or not reproducible. In this paper we propose the accurate liquid chromatographic determination of glycolate in blood and dialysate as a means to detect type I primary hyperoxaluria in patients on maintenance hemodialysis (RDT). The method is based on the enzymatic conversion of glycolate to glyoxylate coupled with alpha-keto acid derivatization with phenylhydrazine. The resulting phenylhydrazone is then resolved by high-performance liquid chromatograph (HPLC). With this method, plasma glycolate in 12 healthy controls was 7.8 +/- 1.7 mumol/liter, almost twentyfold less than previously reported. Five dialysis patients with high serum oxalate, of whom four with primary hyperoxaluria and one with Crohn's disease and presumed enteric oxalate hyperabsorption, were checked by this method and compared to nine patients with oxalosis-unrelated ESRD. The patients with hyperoxalemia were also evaluated for their response to pyridoxine therapy. The measurement of glycolate in blood drawn prior to and at the end of the dialysis session as well as in the dialysate soundly discriminated the patients with type I hyperoxaluria from all the other dialysis patients. Glycolate measurement was shown to be much more powerful than oxalate in that patients with oxalosis-induced ESRD exhibited an almost two hundred and fiftyfold increase compared to the oxalosis-unrelated patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Hyperoxaluria or hypercalciuria in nephrolithiasis: the importance of renal tubular functions.

The role of the kidney in states of hyperoxaluria and hypercalciuria was investigated in seven patients with hyperoxaluria after jejunoileal bypass (JIB) and six patients with idiopathic hypercalciuria (IHC). Eight apparently healthy persons formed a control group. Besides hyperoxaluria, the patients with JIB displayed an elevated plasma concentration of oxalate and the oxalate clearance was increased and higher than creatinine clearance, indicating a net tubular secretion of oxalate. The JIB patients had lower 24-h urinary excretions of calcium, phosphate, magnesium and citrate and higher serum parathyroid hormone (PTH) than controls, indicating increased secretion of PTH to compensate for calcium malabsorption. IHC patients exhibited increased fasting urinary calcium even though their serum values were similar to those in the controls. These results indicate a reduced tubular calcium reabsorption, which was most pronounced in patients with highest PTH values. We conclude that hyperoxaluria in JIB patients is associated both with intestinal hyperabsorption and with enhanced tubular secretion of oxalate, and that in some patients with IHC hypercalciuria is due to reduced tubular reabsorption of calcium.

Adult↗