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Cowley DM, McWhinney BC, Brown JM, Chalmers AH. Effect of citrate on the urinary excretion of calcium and oxalate: relevance to calcium oxalate nephrolithiasis. Clin Chem 1989. [DOI: 10.1093/clinchem/35.1.23] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Abstract
Studies in 24 recurrent oxalate stone-formers have shown that values for urinary calcium excretion for this group on at-home diets vary significantly (P less than 0.001) more than values for creatinine excretions. By placing stone-formers on controlled in-hospital diets and measuring their calcium excretions, we were able to predict probable outpatient hypercalciuria (greater than 7.5 mmol/day) with a sensitivity of 95% and a specificity of 95%. In this study, the renal loss of calcium during low-calcium diets was proportional to the absorptive hypercalciuria during high-calcium diets. Calcium loading experiments in fasted stone-formers and normal subjects indicated that citrate, at citrate:calcium molar ratios ranging from 0.12 to 1, stimulated urinary calcium excretion more than did calcium carbonate loading alone. In addition, citrate also significantly (P less than 0.05) increased the excretion of urinary oxalate by two normal subjects for a given load of calcium oxalate. Malabsorption of citrate and possibly other hydroxycarboxylic acids may thus predispose to oxalate nephrolithiasis by promoting calcium and oxalate absorption.
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27
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DeLeacy EA, Cowley DM, Wynne JM. False-positive result of a glucose tolerance test. Med J Aust 1988; 149:225-6. [PMID: 3173184 DOI: 10.5694/j.1326-5377.1988.tb120583.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Cowley DM, Pabari M, Sinton TJ, Johnson S, Carroll G, Ryan WE. Pathogenesis of postoperative hyponatraemia following correction of scoliosis in children. THE AUSTRALIAN AND NEW ZEALAND JOURNAL OF SURGERY 1988; 58:485-9. [PMID: 3077898 DOI: 10.1111/j.1445-2197.1988.tb06240.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Eight paediatric patients undergoing major surgery for correction of scoliosis who were treated postoperatively with hypotonic saline and 5% dextrose have been studied. Plasma sodium, renin and aldosterone, and urine volume, sodium and osmolality were measured. These patients had an impaired ability to excrete a sodium-free water load. In the first 60 h urine volume remained reduced, while in the first 36 h urine sodium remained concurrently high. If the first 36 h postoperation are considered, the sodium-free water given was quantitatively retained and the serum sodium at 36 h was significantly correlated with the amount of free water given (P less than 0.01). To minimize postoperative hyponatraemia and the associated shift of water into the brain causing cerebral oedema, it is recommended that no more than 50 ml/kg sodium-free water be given until urine sodium falls and volume increases.
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Chalmers AH, Cowley DM, Brown JM, McWhinney BC. More on citric acid and calcium nephrolithiasis. Clin Chem 1988; 34:793. [PMID: 3359632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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30
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Chalmers AH, Cowley DM, Brown JM, McWhinney BC. More on citric acid and calcium nephrolithiasis. Clin Chem 1988. [DOI: 10.1093/clinchem/34.4.793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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31
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Brown JM, Stratmann G, Cowley DM, Mottram BM, Chalmers AH. The variability and dietary dependence of urinary oxalate excretion in recurrent calcium stone formers. Ann Clin Biochem 1987; 24 ( Pt 4):385-90. [PMID: 3662388 DOI: 10.1177/000456328702400407] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Twenty-two recurrent calcium stone formers had 24-h urinary oxalate excretions on their home diets which were significantly greater than those of 30 normal subjects (0.48 +/- 0.23 mmol/d; mean +/- SD compared with 0.31 +/- 0.11; P less than 0.01). The stone formers also demonstrated marked day to day variability in oxalate excretion indicating that a single normal urinary oxalate measurement did not exclude significant hyperoxaluria at other times. On a hospital diet containing 1000 mg calcium per day, urinary oxalate excretion fell significantly from 0.48 +/- 0.23 mmol/d to 0.32 +/- 0.12; P less than 0.01. As the urinary calcium excretion in and out of hospital was similar, it seems unlikely that low calcium intake at home was responsible for the hyperoxaluria. All patients had recurrent symptomatic stone disease and had been advised to avoid foods rich in oxalate. Whilst poor compliance is a possible explanation for the variability in oxalate excretion, we believe it is more likely that there is an inadvertent intake of oxalogenic precursors in their diet. As normal subjects do not demonstrate hyperoxaluria on similar home diets, stone formers may have a metabolic defect in the handling of these precursors.
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32
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McWhinney BC, Nagel SL, Cowley DM, Brown JM, Chalmers AH. Two-carbon oxalogenesis compared in recurrent calcium oxalate stone formers and normal subjects. Clin Chem 1987; 33:1118-20. [PMID: 3594837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
We used a xylitol load to test the two-carbon pathway to oxalate production in humans. Use of this pentose sugar caused a fourfold increase in glycolate excretion, indicating its suitability as a dynamic function test of two-carbon metabolism. However, despite this increase in glycolate excretion in 10 recurrent stone formers and six normal subjects, there was no concomitant increase in oxalate excretion in either group. By comparison, a sucrose load produced no increase in excretion of either glycolate or oxalate. In addition, when we studied four recurrent calcium stone formers on successive diets with various fat content, we found no correlation between high fat intake and increased glycolate or oxalate excretion. In summary, there was no evidence of abnormal fluxes through the two-carbon pathway to oxalate in recurrent stone formers, nor of hyperoxaluria as related to increased intake of sucrose or fat.
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33
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McWhinney BC, Nagel SL, Cowley DM, Brown JM, Chalmers AH. Two-carbon oxalogenesis compared in recurrent calcium oxalate stone formers and normal subjects. Clin Chem 1987. [DOI: 10.1093/clinchem/33.7.1118] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Abstract
We used a xylitol load to test the two-carbon pathway to oxalate production in humans. Use of this pentose sugar caused a fourfold increase in glycolate excretion, indicating its suitability as a dynamic function test of two-carbon metabolism. However, despite this increase in glycolate excretion in 10 recurrent stone formers and six normal subjects, there was no concomitant increase in oxalate excretion in either group. By comparison, a sucrose load produced no increase in excretion of either glycolate or oxalate. In addition, when we studied four recurrent calcium stone formers on successive diets with various fat content, we found no correlation between high fat intake and increased glycolate or oxalate excretion. In summary, there was no evidence of abnormal fluxes through the two-carbon pathway to oxalate in recurrent stone formers, nor of hyperoxaluria as related to increased intake of sucrose or fat.
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34
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Cowley DM, McWhinney BC, Brown JM, Chalmers AH. Chemical factors important to calcium nephrolithiasis: evidence for impaired hydroxycarboxylic acid absorption causing hyperoxaluria. Clin Chem 1987; 33:243-7. [PMID: 3802507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
An investigation of variables important to calcium stone formation in urine indicated significantly increased daily excretion of calcium and oxalate and decreased excretion of ascorbate and citrate by recurrent calcium stone formers. In addition, urine volume, sodium, mucopolysaccharide, and protein were also significantly increased. We compared the uptake of citrate and ascorbate from the gut into the blood in normal controls and stone formers. These studies indicated significantly depressed absorption of both these hydroxycarboxylic acids in recurrent calcium stone formers. We also found that concurrent administration of citrate inhibited ascorbate absorption and increased urinary oxalate excretion after an ascorbate load in normal subjects and stone formers. These findings suggest a mechanism that explains hyperoxaluria in stone patients on the basis of a malabsorption of citrate, ascorbate, and possibly other hydroxycarboxylic acids.
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35
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McWhinney BC, Cowley DM, Chalmers AH. Simplified column liquid chromatographic method for measuring urinary oxalate. JOURNAL OF CHROMATOGRAPHY 1986; 383:137-41. [PMID: 3818831 DOI: 10.1016/s0378-4347(00)83451-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Sinton TJ, De Leacy EA, Cowley DM. Comparison of 51Cr EDTA clearance with formulae in the measurement of glomerular filtration rate. Pathology 1986; 18:445-7. [PMID: 3103081 DOI: 10.3109/00313028609087566] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The need exists for a fast and accurate method of estimating glomerular filtration rate (GFR). A number of nomograms and formulae which estimate GFR on the basis of a plasma creatinine level have appeared in the literature. We examined some of these nomograms and formulae and showed that when the formula published by Cockcroft and Gault was compared with the GFR as estimated by 51Cr EDTA clearance, the coefficient of correlation was better than 0.94. We also compared creatinine clearance with the Cockcroft and Gault formula, and the Siersbaek-Nielsen nomogram. In each case, the correlation coefficient was less than that for the Cockcroft and Gault-51Cr EDTA comparison. Because of the inherent difficulties in making accurate 24 h urine collections, and problems associated with 51Cr EDTA studies, it is suggested that the formula prediction of GFR is more reliable than a GFR estimate using a 24 h collection.
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Tudehope DI, Mitchell F, Cowley DM. A comparative study of a premature infant formula and preterm breast milk for low birthweight infants. AUSTRALIAN PAEDIATRIC JOURNAL 1986; 22:199-205. [PMID: 3767788 DOI: 10.1111/j.1440-1754.1986.tb00223.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Although the unique composition of preterm milk (PTM) has led to its increasing use in feeding of low birthweight (LBW) infants, controversy exists as to whether such milk adequately meets their requirements. This study compares the clinical tolerance and anthropometric, biochemical and haematological parameters of LBW infants fed exclusively with their own mother's PTM, a premature infant formula (Alprem; Nestlé Australia) and a mixture of PTM and Alprem. Of 90 enrolled LBW infants (1000-1750 g birthweight), 78 completed the feeding trial for a mean duration of 42 days. Twenty-eight babies were fed Alprem (Group A), 31 received a mixture of Alprem and PTM (Group B) and 18 received PTM (Group C). Babies in Groups A and B were smaller, less mature and more asphyxiated at birth than those in Group C. Weight gain from full enteral feeding was greater in Group A (18.1 g/kg per day) and Group B (17.6 g/kg per day) than in Group C (13.0 g/kg per day). Throughout the trial, weight gain in Groups A and B exceeded predicted intra-uterine growth rates, whereas that for Group C approximated the predicted intra-uterine growth rates. Growth rates of length and head circumference were also greatest in the Alprem-fed babies. Infants receiving PTM were supplemented with calcium, sodium, vitamins and energy, whereas the only three infants requiring mineral supplementation in the Alprem group were those receiving Frusemide therapy for chronic lung disease. lower serum concentrations of phosphorus, iron, albumin and urea, and higher zinc and alkaline phosphatase concentrations were found in infants receiving PTM (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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Abstract
We have devised a simple, sensitive quantitative method for the determination of serum methemalbumin. The method uses a modified Allen correction to correct the alpha band of methemalbumin at 623 nm for background turbidity. The technique is robust and is more sensitive than Schumm's test.
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40
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Cowley DM, Mottram BM, Haling NB, Sinton TJ. Improved linearity of the calcium-cresolphthalein complexone reaction with sodium acetate. Clin Chem 1986; 32:894-5. [PMID: 3698286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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41
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Cowley DM, Mottram BM, Haling NB, Sinton TJ. Improved linearity of the calcium-cresolphthalein complexone reaction with sodium acetate. Clin Chem 1986. [DOI: 10.1093/clinchem/32.5.894a] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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42
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Chalmers AH, Cowley DM, Brown JM. A possible etiological role for ascorbate in calculi formation. Clin Chem 1986; 32:333-6. [PMID: 3943193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Studies of recurrent stone formers indicated that they have significantly increased urinary oxalate and decreased ascorbate excretions. Results of oral and intravenous administration of ascorbate indicate an enhanced production of oxalate from ascorbate in recurrent calcium stone formers as compared with normal persons and that most of this oxalate is generated in the gut.
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43
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Abstract
Abstract
Studies of recurrent stone formers indicated that they have significantly increased urinary oxalate and decreased ascorbate excretions. Results of oral and intravenous administration of ascorbate indicate an enhanced production of oxalate from ascorbate in recurrent calcium stone formers as compared with normal persons and that most of this oxalate is generated in the gut.
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44
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Burke JR, Cowley DM, Mottram BM, Buckner P. Cellulose phosphate and chlorothiazide in childhood idiopathic hypercalciuria. AUSTRALIAN AND NEW ZEALAND JOURNAL OF MEDICINE 1986; 16:43-7. [PMID: 3458445 DOI: 10.1111/j.1445-5994.1986.tb01114.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A calcium loading test performed on seven of eight children with idiopathic hypercalciuria identified the hyperabsorptive form of hypercalciuria in five and renal hypercalciuria in one. The type of hypercalciuria was not identified in the other patient. Three children presented with hematuria without calculus formation. Chlorothiazide reduced the urinary calcium excretion level in two of six patients to the normal range. The addition of cellulose phosphate to chlorothiazide reduced the urinary calcium excretion level to the normal range in those four patients who showed an incomplete response to chlorothiazide alone. There was clinical improvement with cellulose phosphate in another child whose symptoms did not disappear after chlorothiazide had reduced urinary calcium level to the normal range. Cellulose phosphate is effective in children with recurrent stone formation who have shown inadequate response to chlorothiazide.
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45
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Sinton TJ, Cowley DM, Bryant SJ. Reference intervals for calcium, phosphate, and alkaline phosphatase as derived on the basis of multichannel-analyzer profiles. Clin Chem 1986; 32:76-9. [PMID: 3940739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
In an attempt to demonstrate a rapid and economical approach to deriving reference intervals, we analyzed data on plasma calcium and phosphate from a multichannel analyzer for more than 20 000 subjects and data on alkaline phosphatase from more than 10 000 subjects. Subjects were selected by the criterion, that their results for constituents other than the one of interest were within current reference intervals. Thus we have been able to include older patients who have diseases that accompany old age, but that do not affect test results. The mean concentrations of calcium and phosphate decreased with increasing age in both sexes, except for an abrupt increase for women about the time of reaching menopause. Similarly, the mean alkaline phosphatase activity increased with age in both sexes, reflecting a skewed frequency distribution. Here also, there was an abrupt increase in the modal value for women near menopause.
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46
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Sinton TJ, Cowley DM, Bryant SJ. Reference intervals for calcium, phosphate, and alkaline phosphatase as derived on the basis of multichannel-analyzer profiles. Clin Chem 1986. [DOI: 10.1093/clinchem/32.1.76] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Abstract
In an attempt to demonstrate a rapid and economical approach to deriving reference intervals, we analyzed data on plasma calcium and phosphate from a multichannel analyzer for more than 20 000 subjects and data on alkaline phosphatase from more than 10 000 subjects. Subjects were selected by the criterion, that their results for constituents other than the one of interest were within current reference intervals. Thus we have been able to include older patients who have diseases that accompany old age, but that do not affect test results. The mean concentrations of calcium and phosphate decreased with increasing age in both sexes, except for an abrupt increase for women about the time of reaching menopause. Similarly, the mean alkaline phosphatase activity increased with age in both sexes, reflecting a skewed frequency distribution. Here also, there was an abrupt increase in the modal value for women near menopause.
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47
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Chalmers AH, Cowley DM, McWhinney BC. Stability of ascorbate in urine: relevance to analyses for ascorbate and oxalate. Clin Chem 1985; 31:1703-5. [PMID: 3930094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Ascorbate is unstable in urine at room temperature at pH values ranging from 1 to 12. At pH 7 and above, oxalate is generated in amounts directly proportional to the ascorbate concentration. In 12 different urines, adjusted to pH 12 and incubated for 20 h at room temperature, there was a significant correlation between the amount of oxalate formed and the initial ascorbate concentration (r = 0.97, p less than 0.01). The mean (+/- SD) concentration of oxalate (1.32 +/- 0.70 mmol/L) formed during this period approximated the initial ascorbate concentration (1.57 +/- 1.09 mmol/L). Disodium EDTA, 10 mmol/L final concentration, stabilizes ascorbate in urine and inhibits its conversion to oxalate at pH values of 4.4 to 7.0 during a 24-h period. We therefore propose that urine specimens for ascorbate and oxalate analyses be collected with disodium EDTA present such as to give about this final concentration.
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48
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Chalmers AH, Cowley DM, McWhinney BC. Stability of ascorbate in urine: relevance to analyses for ascorbate and oxalate. Clin Chem 1985. [DOI: 10.1093/clinchem/31.10.1703] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Abstract
Ascorbate is unstable in urine at room temperature at pH values ranging from 1 to 12. At pH 7 and above, oxalate is generated in amounts directly proportional to the ascorbate concentration. In 12 different urines, adjusted to pH 12 and incubated for 20 h at room temperature, there was a significant correlation between the amount of oxalate formed and the initial ascorbate concentration (r = 0.97, p less than 0.01). The mean (+/- SD) concentration of oxalate (1.32 +/- 0.70 mmol/L) formed during this period approximated the initial ascorbate concentration (1.57 +/- 1.09 mmol/L). Disodium EDTA, 10 mmol/L final concentration, stabilizes ascorbate in urine and inhibits its conversion to oxalate at pH values of 4.4 to 7.0 during a 24-h period. We therefore propose that urine specimens for ascorbate and oxalate analyses be collected with disodium EDTA present such as to give about this final concentration.
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49
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Chalmers AH, Cowley DM. Stabilization of the reaction mixture used in urinary citrate estimations. Clin Chem 1985. [DOI: 10.1093/clinchem/31.9.1579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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50
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McWhinney BC, Cowley DM, Chalmers AH. An automated method for measuring plasma citrate without protein precipitation. Clin Chem 1985; 31:1578-9. [PMID: 4028416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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