Albumin determination in frozen urines —underestimated results

Erman, Arie; Rabinov, M; Rosenfeld, Joseph B.

doi:10.1016/0009-8981(88)90051-4

Cited by 33 publications

(16 citation statements)

References 7 publications

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“…Long-term storage of urine samples will cause some degradation of albumin. 53 Previously, we had shown that over a period of 15 months, the relative degree of degradation is independent of the initial albumin concentration. 54 In the present study, we analyzed the effect of urinary A/C ratio based on the relative ranking in deciles; thus, degradation of albumin should not affect our results.…”

Section: Discussionmentioning

confidence: 98%

Urinary Albumin Excretion

Borch‐Johnsen

Feldt‐Rasmussen

Strandgaard

et al. 1999

ATVB

373

114

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Abstract-Cross-sectional studies suggest that an increased urinary albumin excretion rate is associated with cardiovascular disease, dyslipidemia, and hypertension. The purpose of this study was to analyze prospectively whether the urinary albumin-to -creatinine (A/C) ratio can independently predict ischemic heart disease (IHD) in a population-based cohort. In 1983, urinary albumin and creatinine levels were measured, along with the conventional atherosclerotic risk factors, in 2085 consecutive participants without IHD, renal disease, urinary tract infection, or diabetes mellitus. The participants were followed up until death, emigration, or December 31, 1993. IHD was defined as a hospital discharge diagnosis or cause of death including the diagnoses ICD-8 and 410 to 414. Seventy-nine individuals developed IHD during the 21 130 person-years of follow-up. They were characterized by a preponderance of males and higher age, body mass index, blood pressure, lipoproteins, and proportion of current smokers. Microalbuminuria was defined as an A/C ratio) Ͼ90 percentile (Ͼ0.65 mg/mmol). When adjusted for other risk factors, the relative risk of IHD associated with microalbuminuria was 2.3 (95% CI, 1.3 to 3.9, Pϭ0.002), and the 10-year disease-free survival decreased from 97% to 91% (PϽ0.0001) when microalbuminuria was present. An interaction between microalbuminuria and smoking was observed, and the presence of microalbuminuria more than doubled the predictive effect of the conventional atherosclerotic risk factors for development of IHD. It is concluded that microalbuminuria is not only an independent predictor of IHD but also substantially increases the risk associated with other established risk factors. Key Words: urinary albumin excretion Ⅲ microalbuminuria Ⅲ ischemic heart disease Ⅲ atherosclerosis M icroalbuminuria, ie, slightly elevated urinary albumin excretion, was initially demonstrated in patients with diabetes mellitus, where it was shown to be associated with atherogenic changes in the cardiovascular risk profile, 1,2 and to predict increased mortality and cardiovascular disease. [3][4][5][6][7][8][9][10][11][12] Several studies have demonstrated an association between slightly increased urinary albumin excretion and cardiovascular risk factors, even in the general population. [13][14][15][16][17][18][19] In the Copenhagen City Heart Study, we found that otherwisehealthy individuals with a urinary albumin excretion level Ͼ90th percentile (Ͼ7 g/min) were characterized by higher blood pressures and lower plasma concentrations of apolipoprotein A-1 and HDL cholesterol. 20 Furthermore, they had a generalized transvascular leakiness for albumin. 21 These observations suggest that individuals with slightly increased urinary albumin excretion may be at increased risk for the subsequent development of ischemic heart disease (IHD). The pathogenic mechanisms leading to increased risk are still unknown, but microalbuminuria has been suggested as a marker of endothelial dysfunction and hyperpermeability to macromolecul...

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Section: Discussionmentioning

confidence: 98%

Urinary Albumin Excretion

Borch‐Johnsen

Feldt‐Rasmussen

Strandgaard

et al. 1999

ATVB

373

114

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“…Although there is general agreement that albumin levels in urine stored at 4~ remain stable for periods up to 8 weeks [12][13][14][15][16][17][18][19] very little is known concerning storage at room temperature and there is considerable controversy as to the effect of storing urine frozen at -20 ~ and the effect of pH and removal of sediment by centrifugation on urinary albumin measurements. Using a variety of different methods of urine albumin estimation some investigators have shown a reduction of urine albumin concentration after frozen storage at -20~ for periods as short as 7 days, 2 and 6 weeks [18][19][20] and after periods of 2, 6 and 24 months [19,21,22]. However, other investigators have found no significant effect of frozen storage at -20 ~ on urine albumin over similar periods ranging from 10 days [12] …”

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confidence: 99%

Storage temperature and differing methods of sample preparation in the measurement of urinary albumin

et al. 1993

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Microalbuminuria is a predictor of persistent proteinuria, renal failure and cardiovascular disease and therefore accurate determination of urinary albumin concentration is important. We examined the stability of albumin in urine under different conditions of storage, temperature and sample preparation. There was no significant difference in urinary albumin concentration between fresh urine and urine stored at either 4 degrees C or 20 degrees C for up to 7 days. Similarly in urine samples from diabetic patients there was no significant difference in albumin concentration at levels ranging from 1.3 to 1999.3 mg/l between fresh urine at 4 degrees C and urine stored frozen for 1 week, 1 month or 6 months. Neither storage temperature (-20 degrees C or -40 degrees C) nor centrifugation of sample prior to assay made a significant difference to the albumin concentration. Multiple freezing and thawing of urine samples during 6 weeks of storage at -20 degrees C made no difference to albumin concentrations. Storage of urine samples in either polypropylene, polystyrene or borosilicate glass tubes did not result in a significant change in urinary albumin concentration after either 1 week or 1 month at -20 degrees C although, after 1 month of storage, urinary albumin concentrations tended to be lower by an average of approximately 7%. In tubes to which gelatine had been added this was reduced to 4%. We conclude that fresh urine can be kept at 4 degrees C or 20 degrees C for up to 7 days. Frozen urine samples can be stored for up to 6 months before assay without any loss of albumin concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

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“…This subgroup also differed from the remaining patients with BH lead to underestimation of the albumin concentration. 29 and normal ex-UAE in that they had greater 24 h-UAE. However, there were no differences between There have been only three studies addressing 24 h-UAE in BH.…”

Section: Resultsmentioning

confidence: 87%