Quantification of hypercalciuria with the urine calcium osmolality ratio in children

Mır, Sevgı; Serdaroğlu, Erkin

doi:10.1007/s00467-005-1992-8

Cited by 31 publications

(18 citation statements)

References 16 publications

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“…In parallel, sodium oxalate (NaOx; at final concentrations of 0, 1.25, 2.5, 5, 10 and 20 mM) and sodium chloride (NaCl; at final concentrations of 0, 12.5, 25, 50, 100 and 200 mM) were also challenged to the individual centrifuged urine samples. Note that the concentrations of NaOx added were 10 times less than those of CaCl 2 because the oxalate level in the normal urine was about one-tenth of the normal urinary calcium level (22).…”

Section: Methodsmentioning

confidence: 99%

“…We intentionally used this series of NaOx concentrations in relation to the normal level of urinary oxalate, which is usually one-tenth of the normal urinary calcium level (22). CaCl 2 was added to the urine samples by varying concentrations from 12.5 to 200 mM, which were 2.5-40 times greater than the upper limit of the normal urinary calcium level (ϳ5 mM) (22).…”

Section: Fig 2 Effect Of Removal Of Cells and Debrismentioning

confidence: 99%

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Characterizations of urinary sediments precipitated after freezing and their effects on urinary protein and chemical analyses

Saetun¹,

Semangoen²,

Thongboonkerd³

2009

American Journal of Physiology-Renal Physiology

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One of the obstacles in analyzing frozen urine samples is the formation of uncharacterized precipitates. Frequently, these precipitates are discarded before analysis. Some laboratory data may be erroneous if these precipitates contain important compounds. In the present study, we examined urinary sediments precipitated after overnight storage at -20 degrees C. Although cells and debris were removed before freezing, the precipitates remained, whereas storing the centrifuged urine overnight at 4 degrees C did not result in precipitate formation. There were no significant differences observed among 10 healthy individuals (5 men and 5 women). EDTA (5 mM) could efficiently reduce the amount of precipitates to approximately 25% of the initial amount. The addition of exogenous CaCl2, but not sodium oxalate and NaCl, significantly increased the amount of precipitates in a dose-dependent manner. Linear regression analysis revealed a significant correlation between endogenous urinary calcium level and the amount of precipitates (r = 0.894; P < 0.001). Urine pH also had some effects on the type and amount of precipitates. These precipitates were composed mainly of calcium oxalate dihydrate and amorphous calcium crystals. The results also showed that these precipitates could deplete urinary proteins and calcium ions (23.6 +/- 1.1% decrease). Therefore, these freezer-induced urinary sediments significantly affect protein analysis and measurement of calcium levels in the urine. However, vigorous shaking of the sample at room temperature could redissolve these precipitates. Our data strongly indicate that these freezer-induced precipitates must be taken into account when the frozen urine samples are analyzed.

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Section: Methodsmentioning

confidence: 99%

Section: Fig 2 Effect Of Removal Of Cells and Debrismentioning

confidence: 99%

Characterizations of urinary sediments precipitated after freezing and their effects on urinary protein and chemical analyses

Saetun¹,

Semangoen²,

Thongboonkerd³

2009

American Journal of Physiology-Renal Physiology

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“…In children and young adults consuming a typical affluent Western-type diet urea excretion contributes to about 40% and sodium chloride to about 35-44% of total renal solute excretion [8,10]. A rise of sodium excretion increases the values of urinary calcium and osmolality [11].…”

Section: Introductionmentioning

confidence: 99%

Upper metastable limit osmolality of urine as a predictor of kidney stone formation in children

et al. 2018

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High fluid intake has been universally recommended for kidney stone prophylaxis. We evaluated 24-h urine osmolality regarded as the best biomarker of optimal hydration and upper metastable limit osmolality after water evaporation from urine sample to the onset of spontaneous crystallization and its usefulness as a new risk index that would describe an individual lithogenic potential. We collected 24-h urine from 257 pediatric patients with kidney stones and 270 controls. After volume and osmolality assessment, the urine samples were subjected to volume reduction in vacuum rotavapor continued to the onset of an induced urinary crystallization. The upper metastable limit osmolality of urine sample was calculated based on its initial osmolality value and the amount of water reduction. Pediatric stone formers presented with higher urine volume and lower urine osmolality than healthy controls. Despite that, their urine samples required much lower volume reduction to induce the spontaneous crystallization than those of controls. The ROC analysis revealed an AUC for the upper metastable limit osmolality of 0.9300 (95% CI 0.9104-0.9496) for distinguishing between stone formers and healthy subjects. At the cutoff of 2696 mOsm/kg, the test provided sensitivity and specificity of 0.8638 and 0.8189, respectively. 24-h urine osmolality provided the information about current hydration status, whereas evaporation test estimated the urinary potential to crystalize dependent on urine composition. Upper metastable limit osmolality may estimate the individual lithogenic capability and identify people at risk to stone formation when exposed to dehydration.

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“…In the absence of disease, creatinine concentrations in serum and urine are usually very stable and can be used to estimate the urinary excretion of substances with only spot urine samples (21)(22)(23)(24). Therefore, in this study, we expressed total urinary polyphenol excretion per grams of creatinine excreted in the urine rather than per milliliters of urine.…”

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confidence: 99%

Total Polyphenol Intake Estimated by a Modified Folin–Ciocalteu Assay of Urine

et al. 2006

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adrenocorticotropin test in the assessment of hypothalamic-pituitary-adrenal function. Eur J Endocrinol 1998;139:575-9 Background: Plant polyphenols have been studied largely because of the possibility that they might underlie the protective effects afforded by fruit and vegetable intake against cancer and other chronic diseases. Measurement of polyphenol content excreted in urine as an indicator of polyphenol consumption may offer a routine screening method that could be used for these pathologies. Methods: Thirty-six healthy volunteers each received 2 interventions, one with a polyphenol-rich food (cocoa beverage) and one with a polyphenol-free food (milk) as a control, in a randomized cross-over design with 1-week intervals. The total polyphenol content excreted in urine during the 6 h after consumption of the test meals was measured by a modified Folin-Ciocalteu assay after sample cleanup by solid-phase extraction.

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Quantification of hypercalciuria with the urine calcium osmolality ratio in children

Cited by 31 publications

References 16 publications

Characterizations of urinary sediments precipitated after freezing and their effects on urinary protein and chemical analyses

Characterizations of urinary sediments precipitated after freezing and their effects on urinary protein and chemical analyses

Upper metastable limit osmolality of urine as a predictor of kidney stone formation in children

Total Polyphenol Intake Estimated by a Modified Folin–Ciocalteu Assay of Urine

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