Stability of urine creatinine

Spierto, F. W.; Hannon, W. Harry; Gunter, Elaine W.; Smith, Steven J.

doi:10.1016/s0009-8981(97)00080-6

Cited by 54 publications

(27 citation statements)

References 10 publications

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“…Creatinine is stable for up to 2 years when stored at -20°C or -80°C, while at 4°C it is stable for 30 days. 32 Cystatin C is stable for 7 days at both 4°C and -20°C and for 48 h at 20°C, for up to three freeze/thaw cycles and at pH > 5. 33 It has recently been shown that post-centrifugation delays of up to 48 hours at either RT or 4°C do not have a significant impact on the levels of biomarkers of acute kidney injury (neutrophil gelatinase-associated lipocalin, interleukin-18, kidney injury molecule 1, liver-type fatty acid-binding protein).…”

Section: Urine Processing Methods 355 Discussionmentioning

confidence: 97%

Method Validation for Preparing Urine Samples for Downstream Proteomic and Metabolomic Applications

Ammerlaan

Trezzi

Mathay

et al. 2014

Biopreservation and Biobanking

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Background: Formal validation of methods for biospecimen processing in the context of accreditation in laboratories and biobanks is lacking. A protocol for processing of a biospecimen (urine) was validated for fitness-for-purpose in terms of key downstream endpoints. Methods: Urine processing was optimized for centrifugation conditions on the basis of microparticle counts at room temperature (RT) and at 4°C. The optimal protocol was validated for performance (microparticle counts), and for reproducibility and robustness for centrifugation temperature (4°C vs. RT) and brake speed (soft, medium, hard). Acceptance criteria were based on microparticle counts, cystatin C and creatinine concentrations, and the metabolomic profile. Results: The optimal protocol was a 20-min, 12,000 g centrifugation at 4°C, and was validated for urine collection in terms of microparticle counts. All reproducibility acceptance criteria were met. The protocol was robust for centrifugation at 4°C versus RT for all parameters. The protocol was considered robust overall in terms of brake speeds, although a hard brake gave significantly fewer microparticles than a soft brake. Conclusions: We validated a urine processing method suitable for downstream proteomic and metabolomic applications. Temperature and brake speed can influence analytic results, with 4°C and high brake speed considered optimal. Laboratories and biobanks should ensure these conditions are systematically recorded in the scope of accreditation.

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Section: Urine Processing Methods 355 Discussionmentioning

confidence: 97%

Method Validation for Preparing Urine Samples for Downstream Proteomic and Metabolomic Applications

Ammerlaan

Trezzi

Mathay

et al. 2014

Biopreservation and Biobanking

View full text Add to dashboard Cite

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“…The question, which of the concentration terms: I/cr or I/L is then preferable, depends on technical and financial aspects. The term I/L (I/dL), nowadays recommended by WHO, presents the advantage of the lowest cost, the best technical feasibility and the absence of creatinine variability linked to age, sex, muscle mass, diseases including notably hyper-and hypothyroidism, and pH conditions (Fuller & Elia, 1988;Spierto et al, 1997). This effect of pH on urine creatinine stability would be of special importance to those who routinely use acid for stabilizing their urine specimens.…”

Section: Discussionmentioning

confidence: 99%

Quantification of urinary iodine: a need for revised thresholds

et al. 2003

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Objective: To compare different possibilities of reporting the iodine supply in the same urine samples. Indeed, in field studies, urinary iodine concentration (I/L: mg I/L, mmol I/L, I/creatinine: mg I/g creatanine, mmol I/mol creatinine) is more readily available than excretion (I/24h mg I/24 h, mmol I/24h). However, confusion exists regarding the comparability of iodine supply based upon I/L, I/creatinine and I/24h, which for decades have been regarded as biochemically equivalent. Design: We compared I/24h, I/L and I/creatinine in accurate 24 h collections of urine and I/L and I/creatinine in 47 spot urine samples. Patients: A total of 13 subjects (Bern n ¼ 7, Brussels n ¼ 6) collected a total of 110 precise 24 h urine collections (Bern n ¼ 63, Brussels n ¼ 47). The subjects from Brussels also took a spot sample at the beginning of each 24 h collection. Results: Iodine supply in both places was mildly deficient according to the criteria of WHO; all but one collection indicated an intake of 40.39 mmol I/24h (450 mg I/24h). The same data presented as I/creatinine (or I/L) indicated an iodine intake of o0.39 (o50 mg I/24h) in 5% (24%) of the samples in Bern and 23% (57%) in Brussels. Similar findings were observed for 47 spot samples. Whatever the cut-off selected, I/creatinine and I/L were systematically lower than I/24h (Po0.0002). Creatinine showed smaller CV than volume but did not perform better in defining iodine intake. Conclusion: Considering I/24h as a reference, both I/creatinine and I/L clearly underestimate the iodine intake in subjects with adequate proteoenergetic intake. The significant deviations observed illustrate the urgent need for establishing separate ranges for I/24h, I/creatinine and I/L. In population studies, these deviations might even be larger.

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“…Urines were immediately frozen by the participants at about 7 20 C and transferred in a frozen state every 6 months to the University Hospital of Bern, where they were stored prior to analyses (May to September 1998). It was assumed that concentrations of urinary creatinine did not change during the storage period (Spierto et al, 1997). Stability of UIC and UNaC were controlled in our laboratory (Haldimann & Zimmerli, 1999).…”

Section: Spot Urine Samplingmentioning

confidence: 99%

Swiss pilot study of individual seasonal fluctuations of urinary iodine concentration over two years: is age-dependency linked to the major source of dietary iodine?

et al. 2003

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Objective: Because of known significant seasonal fluctuations of iodine concentration in cow's milk (ICM) in Switzerland (winter=summer (w=s) ICM ratio averages 5.6), we looked for seasonal variations and familial aspects in urinary iodine and sodium concentrations (UIC, UNaC). Design: Prospective sequential cohort investigation. Setting: University hospital. Subjects: Thirteen children (six girls, seven boys) aged 3 -10 y and their parents (n ¼ 9) aged 30 -47 y. Interventions: The volunteers collected 1729 spot urine samples (5.1996 -5.1998). UIC data from winter (UIC w : DecemberFebruary) and summer seasons (UIC s : July -September) were compared with UNaC and average milk consumption. Iodine intakes from milk and salt were modelized. Results: Highest seasonal fluctuations of UIC were found in six pre-school children (w=s UIC group average ¼ 1.56, significant), followed by seven school children (w=s UIC group average ¼ 1.24, N.S.); none existed in adults. UIC=UNaC showed corresponding seasonal fluctuations in children, but not in adults. Winter milk was an important iodine source for children, as proven indirectly by similar seasonal fluctuations of ICM, UIC, UIC=UNaC and an important part within UIC due to milk. Conclusions: Contribution to UIC from milk intake during winter was high in children (40 -50%) and lower in adults (about 20%). Compared with children, dietary habits of adults are more complex and their iodine supply depends mainly on iodized salt and not on milk, so the effect of seasonal ICM variations on UIC is less marked. Because of significant seasonal UIC fluctuations in consumers of fresh milk products in Switzerland, results of future UIC studies conducted during summer and winter seasons should be compared cautiously, especially in young children. Furthermore, consumption of milk is to be promoted, since, besides calcium and vitamins, it is an essential source of iodine. UNaC determination should be included in epidemiologic studies if the dietary source of iodine is questioned. Sponsorship: This work was supported by grants from the University Hospital in Bern, the Swiss Federal Office of Public Health, the 'Swiss National Foundation for Scientific Research' (32-49424.96), the 'Fondation Genevoise de Bienfaisance V Rossi di Montelera', the 'Schweizerische Lebensversicherungs-und Rentenanstalt' and the 'Schüpbach Foundation of the University of Bern'. European Journal of Clinical Nutrition (2003) 57, 636 -646. doi:10.1038=sj.ejcn.1601590 Keywords: iodine; season; milk; child; diet; salt *Correspondence: C Als, Division of Clinical Chemistry, Inselspital, University of Bern, CH-3010 Bern, Switzerland. E-mail: claudine.als@insel.ch Guarantors: C Als, B Zimmerli and M Haldimann. Contributors: CA had the initial idea, wrote and coordinated the project over several years. CA and BZ wrote the manuscript. MH and BZ did the calculations and the statistical evaluations. MH did the analyses of urinary iodine in his laboratory. All contributors helped in planning the study, evaluating the results a...

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Stability of urine creatinine

Cited by 54 publications

References 10 publications

Method Validation for Preparing Urine Samples for Downstream Proteomic and Metabolomic Applications

Method Validation for Preparing Urine Samples for Downstream Proteomic and Metabolomic Applications

Quantification of urinary iodine: a need for revised thresholds

Swiss pilot study of individual seasonal fluctuations of urinary iodine concentration over two years: is age-dependency linked to the major source of dietary iodine?

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