Storage at -80 degrees C decreases the concentration of HPLC-detected urinary albumin: possible mechanisms and implications. Export

@article{citeulike:5054399, abstract = {Background: Urinary albumin is now measured by high-performance liquid chromatography (HPLC) which also detects albumin missed by traditional immunochemical methods. A predictive effect of HPLC-detected albuminuria on mortality has just been reported in the AusDiab study, measuring albuminuria with HPLC after 7 years of -80 degrees C storage. However, there are already some data suggesting that HPLC-detected albuminuria is affected by -80 degrees C storage. We aimed to measure changes in HPLCdetected albuminuria after 2.5 years and find the factors which may be responsible for this alteration. Methods: Urinary albumin was measured by the US Food and Drug Administration approved HPLC Accumin kit. Total free sulfhydryl groups (TFSG) of urine samples were measured by Ellman's reagent. Results: We found a significant 24\% average decrease in HPLC-detected albuminuria and a correlation between the magnitude of decrease and urinary pH. We found a correlation between changes of urinary albumin dimeric to monomeric ratio of stored urine and pH; however, only changes of monomeric form were found to be significant. A correlation was also found between the TFSG of fresh urine samples and pH. Less TFSG could be detected, and a correlation between TFSG and pH was absent in stored urine. Conclusions: We conclude that measurement of albuminuria by HPLC in long-term -80\°C stored urine gives unreliable results. Decrease of HPLC-detected albuminuria is pH-dependent and may be due to the reducing capacity of urine. Prospective studies need to decide whether the predictive properties of HPLC-detected albuminuria decrease during longterm storage.}, author = {Marko', Lajos and Cseh, Judith and Koszegi, Tamas and Szabo', Zoltan and Molnar, Gergo A. and Mohas, Marton and Szigeti, Nora and Wittmann, Istv\'{a}n}, citeulike-article-id = {5054399}, citeulike-linkout-0 = {http://view.ncbi.nlm.nih.gov/pubmed/19557717}, citeulike-linkout-1 = {http://www.hubmed.org/display.cgi?uids=19557717}, issn = {1121-8428}, journal = {Journal of nephrology}, keywords = {hplc, storage, uae}, number = {3}, pages = {397--402}, posted-at = {2009-07-04 11:40:13}, priority = {2}, title = {Storage at -80 degrees C decreases the concentration of HPLC-detected urinary albumin: possible mechanisms and implications.}, url = {http://view.ncbi.nlm.nih.gov/pubmed/19557717}, volume = {22}, year = {2009} }

TY - JOUR ID - citeulike:5054399 L3 - citeulike-article-id:5054399 N2 - Background: Urinary albumin is now measured by high-performance liquid chromatography (HPLC) which also detects albumin missed by traditional immunochemical methods. A predictive effect of HPLC-detected albuminuria on mortality has just been reported in the AusDiab study, measuring albuminuria with HPLC after 7 years of -80 degrees C storage. However, there are already some data suggesting that HPLC-detected albuminuria is affected by -80 degrees C storage. We aimed to measure changes in HPLCdetected albuminuria after 2.5 years and find the factors which may be responsible for this alteration. Methods: Urinary albumin was measured by the US Food and Drug Administration approved HPLC Accumin kit. Total free sulfhydryl groups (TFSG) of urine samples were measured by Ellman's reagent. Results: We found a significant 24% average decrease in HPLC-detected albuminuria and a correlation between the magnitude of decrease and urinary pH. We found a correlation between changes of urinary albumin dimeric to monomeric ratio of stored urine and pH; however, only changes of monomeric form were found to be significant. A correlation was also found between the TFSG of fresh urine samples and pH. Less TFSG could be detected, and a correlation between TFSG and pH was absent in stored urine. Conclusions: We conclude that measurement of albuminuria by HPLC in long-term -80°C stored urine gives unreliable results. Decrease of HPLC-detected albuminuria is pH-dependent and may be due to the reducing capacity of urine. Prospective studies need to decide whether the predictive properties of HPLC-detected albuminuria decrease during longterm storage. IS - 3 JF - Journal of nephrology SN - 1121-8428 EP - 402 TI - Storage at -80 degrees C decreases the concentration of HPLC-detected urinary albumin: possible mechanisms and implications. VL - 22 SP - 397 KW - hplc KW - storage KW - uae AU - Marko', Lajos AU - Cseh, Judith AU - Koszegi, Tamas AU - Szabo', Zoltan AU - Molnar, Gergo AU - Mohas, Marton AU - Szigeti, Nora AU - Wittmann, István PY - 2009///e UR - http://view.ncbi.nlm.nih.gov/pubmed/19557717 ER -