Measurement of urinary cystatin C by particle-enhanced nephelometric                immunoassay: precision, interferences, stability and reference range

Herget–Rosenthal, Stefan; Feldkamp, Thorsten; Volbracht, Lothar; Kribben, Andreas

doi:10.1258/000456304322879980

Cited by 87 publications

(68 citation statements)

References 24 publications

(27 reference statements)

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“…In accordance with our results, former studies did not report considerable interference with albumin and hemoglobin [2,3]. Other endogenous substances that are present in the urine such as calcium, urea and glucose also did not have impact on u-CYSC analysis.…”

Section: Analytical Performancesupporting

confidence: 92%

“…On the other hand, in severe cases of renal tubular damage but practically for all urine samples above 1.0 mg/l of u-CYSC (that is the calibrated range) the test should be repeated after a proper dilution of the urine samples due to the experienced high-dose hook effect. Although u-CYSC is reported to be a reliable marker of tubular dysfunction, up to now only a few automated turbidimetric or nephelometric serum CYSC assays were adapted for urinary measurements [2,3,5,22,23]. Our assay properties seem to be similar or even better than those of others [2,22,23].…”

Section: Analytical Performancementioning

confidence: 88%

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Novel Automated Immune Turbidimetric Assay for Routine Urinary Cystatin-C Determinations

et al. 2018

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Aim: There is no commercially available urinary cystatin-C (u-CYSC) test in the market. Therefore, we optimized and validated an automated immune turbidimetric test for u-CYSC measurements and investigated u-CYSC concentrations in acute and chronic diseases which might lead to renal tubular disorders. Materials & methods: A particle-enhanced immune turbidimetric assay was adapted and validated on a Cobas 8000/c502 analyzer. Urine samples of different patient groups were also analyzed. Results: Our method showed excellent analytical performance. U-CYSC/u-creatinine (u-CREAT) was higher in sepsis-related acute kidney injury group (p < 0.001) compared with controls and to patients with chronic hypertension and Type 2 diabetes. Conclusion: We validated a fast, sensitive, fully automated u-CYSC assay which is ideal for routine use and might be a potential complementary laboratory test to evaluate renal tubular function.

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Section: Analytical Performancesupporting

confidence: 92%

Section: Analytical Performancementioning

confidence: 88%

Novel Automated Immune Turbidimetric Assay for Routine Urinary Cystatin-C Determinations

et al. 2018

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“…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). 34 In order to prevent degradation of more sensitive molecules, a post-centrifugation delay of less than 2 hours at 4°C, storage of urine supernatant at -80°C, and avoiding freeze/thaw cycles is recommended.…”

Section: Urine Processing Methods 355 Discussionmentioning

confidence: 99%

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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“…The tubular injury markers investigated here reflect injury to different segments of the nephron. Kidney injury molecule-1 (KIM-1), N-acetyl-b-D-glucosaminidase (NAG), cystatin C, and b2-microglobulin (b2MG) were measured as markers for proximal tubular damage (20)(21)(22). As a marker of distal tubular damage, we measured heart-type fatty acid-binding protein (H-FABP) (23,24), whereas neutrophil gelatinase-associated lipocalin (NGAL) and monocyte chemoattractant protein-1 (MCP-1) were measured as markers of inflammation (25,26) For quantification of IgG and IgG4, NGAL, b2MG, MCP-1, and H-FABP, we used direct sandwich-ELISAs as previously described (27).…”

Section: Measurement Of Damage Markersmentioning

confidence: 99%

Glomerular and Tubular Damage Markers in Individuals with Progressive Albuminuria

Nauta

Scheven

Meijer

et al. 2013

Clinical Journal of the American Society of Nephrology

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SummaryBackground and objectives Albuminuria is associated with risk for renal and cardiovascular disease. It is difficult to predict which persons will progress in albuminuria. This study investigated whether assessment of urinary markers associated with damage to different parts of the nephron may help identify individuals that will progress in albuminuria.Design, setting, participants, & measurements Individuals were selected from a prospective community-based cohort study with serial follow-up and defined as "progressors" if they belonged to the quintile of participants with the most rapid annual increase in albuminuria, and reached an albuminuria $150 mg/d during follow-up. Patients with known renal disease or macroalbuminuria at baseline were excluded. Each progressor was matched to two control participants, based on baseline albuminuria, age, and sex. Furthermore, damage markers were measured in a separate set of healthy individuals.Results After a median follow-up of 8.6 years, 183 of 8394 participants met the criteria for progressive albuminuria. Baseline clinical characteristics were comparable between progressors and matched controls (n=366). Both had higher baseline albuminuria than the overall population. Urinary excretion of the glomerular damage marker IgG was significantly higher in progressors, whereas urinary excretion of proximal tubular damage markers and inflammatory markers was lower in these individuals compared with controls. Healthy individuals (n=109) had the lowest values for all urinary damage markers measured.Conclusions These data suggest that albuminuria associated with markers of glomerular damage is more likely to progress, whereas albuminuria associated with markers of tubulointerstitial damage is more likely to remain stable.

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Measurement of urinary cystatin C by particle-enhanced nephelometric immunoassay: precision, interferences, stability and reference range

Abstract: Background Urinary excretion of the low molecular weight protein cystatin C is a marker of renal disorders and a good predictor of the severity of acute tubular necrosis. We evaluated the measurement of urinary cystatin C and determined its reference range.

Cited by 87 publications

References 24 publications

Novel Automated Immune Turbidimetric Assay for Routine Urinary Cystatin-C Determinations

Novel Automated Immune Turbidimetric Assay for Routine Urinary Cystatin-C Determinations

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

Glomerular and Tubular Damage Markers in Individuals with Progressive Albuminuria

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