Trachtenberg F, Barregard L. Effect of storage time at -20°C on markers used for assessment of renal damage in children: albumin, γ-glutamyl transpeptidase, N-acetyl-β-D-glucosaminidase and α1-microglobulin.
ACTA ACUST UNITED AC 2010;
44:331-6. [PMID:
20560801 DOI:
10.3109/00365599.2010.492785]
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Abstract
OBJECTIVE
The objective of this study is to examine the influence of storage time at -20°C on the concentration of albumin, γ-glutamyl transpeptidase (γ-GT), N-acetyl-β-D-glucosaminidase (NAG), α(1)-microglobulin (A1M) and creatinine in a large sample of healthy children.
MATERIAL AND METHODS
The New England Children's Amalgam Trial followed 534 children, aged 6-10 at baseline, for 5 years, with annual urine collections. Urine samples were analysed for creatinine, albumin, γ-GT, NAG and A1M concentrations. Repeated measures analysis of covariance was used to model the effect of storage time on these concentrations.
RESULTS
The γ-GT concentration decreased significantly with storage time at -20°C. There was also a limited decrease in NAG. Albumin, A1M and creatinine concentrations did not appear to be affected by storage time at -20°C.
CONCLUSIONS
If it is necessary to interpret results from samples stored for a long time at -20°C, it is advisable to account for storage time in statistical models.
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