Prolonged Frozen Storage of Urine Reduces the Value of Albuminuria for Mortality Prediction

Brinkman, Jacoline W.; Zeeuw, Dick de; Gansevoort, Ronald; Duker, Jacko J.; Kema, Ido P.; Jong, Paul E. de; Bakker, Stephan J. L.

doi:10.1373/clinchem.2006.081471

Cited by 24 publications

(19 citation statements)

References 5 publications

(6 reference statements)

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“…concentrations (1,2 ). Our study shows that frozen storage for at least 4 months and beyond has a profound effect on UACs assessed by HPLC.…”

Section: Discussionmentioning

confidence: 62%

“…In the latter cases, urine samples are often stored frozen before assessment for practical reasons and for prevention of analytical day-to-day variation and drift. We recently showed that 1 year of frozen storage of urine at Ϫ20°C results in an ϳ30% decrease in albumin concentrations, as well as an increase in the measurement error, in particular in samples with initial concentrations in the normoalbuminuric and microalbuminuric ranges (1,2 ). Importantly, this change in urinary albumin concentrations (UACs) induced by frozen storage resulted in a significant decrease in predictive properties of urine albumin for mortality (2 ).…”

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confidence: 99%

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Apparent Loss of Urinary Albumin during Long-term Frozen Storage: HPLC vs Immunonephelometry

Brinkman¹,

Zeeuw²,

Heerspink³

et al. 2007

Clinical Chemistry

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Background: Urinary albumin detection by immunonephelometry is decreased by ϳ30% in samples that have been frozen at ؊20°C. An HPLC method for assessment of urinary albumin that detects immunoreactive and immunochemically nonreactive albumin has been introduced as an alternative to immunonephelometry. We investigated whether this technique is affected by sample temperature, particularly freezing. Methods: Urine samples (n ‫؍‬ 295) were collected from the general population (Prevention of Renal and Vascular End-Stage Disease Study). Samples were assessed by both immunonephelometry and HPLC when fresh and after storage at ؊20°C for 4, 8, and 12 months and at ؊80°C for 12 months. Results: With immunonephelometry, storage for 4, 8, and 12 months at ؊20°C resulted in mean (SD) urine albumin changes of ؊21% (29%), ؊28% (29%), and ؊34% (31) (P <0.001 for trend). Storage at ؊80°C resulted in a 5% (19%) change after 12 months of storage (not significant). With HPLC, storage for 4, 8, and 12 months at ؊20°C resulted in urine albumin changes of ؊33% (28%), ؊43% (24%), and ؊55% (21%; P <0.001 vs immunonephelometry). Storage at ؊80°C resulted in a ؊29% (29%) change (P <0.001 vs immunonephelometry). Conclusion: Loss of albumin after freezing urine depends not only on freezing temperature but also on detection method. Detection of albumin by immuno-

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“…concentrations (1,2 ). Our study shows that frozen storage for at least 4 months and beyond has a profound effect on UACs assessed by HPLC.…”

Section: Discussionmentioning

confidence: 62%

mentioning

confidence: 99%

Apparent Loss of Urinary Albumin during Long-term Frozen Storage: HPLC vs Immunonephelometry

Brinkman¹,

Zeeuw²,

Heerspink³

et al. 2007

Clinical Chemistry

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“…29 Moreover, the Norfolk study measured albumin concentrations from frozen urine samples, which underestimates the real values and therefore may limit the ability to predict mortality. 30 At present, we have no complete explanation for why higher levels of ACR are associated with the risk for cancer. ACR, which is related to renal and endothelial dysfunction, is fre- …”

Section: Discussionmentioning

confidence: 92%

Association of Albuminuria and Cancer Incidence

Jørgensen

Heuch

Jenssen³

et al. 2008

Journal of the American Society of Nephrology

135

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Albuminuria, which is associated with noncardiovascular mortality, might be a result of altered vascular permeability caused by cytokines and other tumor cell products. The aim of this population-based, longitudinal study was to examine whether elevated albumin-to-creatinine ratio (ACR) is associated with cancer incidence. A total of 5425 participants without diabetes or previous cancer in the Tromsø Study were followed; 590 had a first diagnosis of cancer during 10.3 yr of follow-up. The ACR at baseline significantly correlated with the incidence of cancer, even after adjustment for age, gender, body mass index, physical activity, and smoking (P Ͻ 0.001). Participants with ACR in the highest quintile were 8.3-and 2.4-fold more likely to receive a diagnosis of bladder cancer and lung cancer, respectively, compared with those with ACR in the lowest quintile after similar adjustments. It is concluded that albuminuria is associated with cancer incidence in individuals without a history of diabetes, macroalbuminuria, or previous cancer and that it might confer risks of varying magnitude for different types of cancer.

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“…Third, prolonged frozen storage of urine samples may lead to various changes in albumin, 33 underestimate the number of patients with abnormal excretion of albumin 34 and affect its prediction of outcome. 35 However, frozen urine samples are often used in large multicenter studies where albuminuria is determined by a central laboratory, 24,36 and our samples were kept at Ϫ70°C. Fourth, albumin excretion was indexed to creatinine to calculate the UACR.…”

Section: Study Limitationsmentioning

confidence: 99%

Prevalence and Prognostic Value of Elevated Urinary Albumin Excretion in Patients With Chronic Heart Failure

Masson¹,

Latini²,

Milani³

et al. 2010

Circ: Heart Failure

109

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on behalf of the GISSI-HF InvestigatorsBackground-Increased urinary excretion of albumin is an early sign of kidney damage and a risk factor for progressive cardiovascular and renal diseases and heart failure. There is, however, only limited information on the prevalence and prognostic role of urinary albumin excretion in patients with established chronic heart failure. Methods and Results-A total of 2131 patients enrolled in 76 sites participating in the GISSI-Heart Failure trial provided a first morning spot sample of urine at any of the clinical visits scheduled in the trial to calculate the urinary albumin-to-creatinine ratio. The relation between log-transformed urinary albumin-to-creatinine ratio and all-cause mortality (428 deaths, time from urine collection to event or censoring) was evaluated with Cox multivariable models adjusted for all significant risk factors at the time of urine collection, in the study population, and in patients without diabetes or hypertension. Almost 75% of the patients had normal urinary albumin excretion, but 19.9% had microalbuminuria (30 to 299 mg/g creatinine) and 5.4% had overt albuminuria (Ն300 mg/g). There was a progressive, significant increase in the adjusted rate of mortality in the study population (hazard ratio, 1.12; 95% CI, 1.05 to 1.18 per 1-U increase of log(urinary albumin-to-creatinine ratio), Pϭ0.0002) and in the subgroup of patients without diabetes or hypertension. Randomized treatments (n-3 polyunsaturated fatty acids or rosuvastatin) had no major impact on albumin excretion. Conclusions-Independently of diabetes, hypertension, or renal function, elevated albumin excretion is a powerful prognostic marker in patients with chronic heart failure. (Circ Heart Fail. 2010;3:65-72.)

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Prolonged Frozen Storage of Urine Reduces the Value of Albuminuria for Mortality Prediction

Cited by 24 publications

References 5 publications

Apparent Loss of Urinary Albumin during Long-term Frozen Storage: HPLC vs Immunonephelometry

Apparent Loss of Urinary Albumin during Long-term Frozen Storage: HPLC vs Immunonephelometry

Association of Albuminuria and Cancer Incidence

Prevalence and Prognostic Value of Elevated Urinary Albumin Excretion in Patients With Chronic Heart Failure

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