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
Аннотация: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), α1-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.
