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Martínez F, Pichler G, Ruiz A, Martín-Escudero JC, Chaves FJ, Gonzalez-Albert V, Tellez-Plaza M, Heerspink HJL, Zeeuw DDE, Redon J. Immune-unreactive urinary albumin as a predictor of cardiovascular events: the Hortega Study. Nephrol Dial Transplant 2019; 34:633-641. [PMID: 29788140 DOI: 10.1093/ndt/gfy087] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2017] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND We aimed to determine if immune-unreactive albumin excretion (IURAE) is associated with cardiovascular (CV) events in a representative sample of a general population from Spain. METHODS We included 1297 subjects (mean age ± standard error 48.0 ± 0.2 years, 48% females), who participated in the Hortega Follow-Up Study. The primary endpoint was incidence of fatal and non-fatal CV events. Urinary albumin excretion (UAE) was measured in spot voided urine, frozen at -80°C, by immunonephelometry [immune-reactive albumin excretion (IRAE)] and by high-performance liquid chromatography (HPLC) [total albumin excretion (AE)]. IURAE was calculated as the difference between HPLC measurements and IRAE. We estimated fully adjusted hazard ratios (HRs) of CV incidence by Cox regression for IRAE, IURAE and total AE. RESULTS After an average at-risk follow-up of 13 years, we observed 172 CV events. urinary albumin to creatinine ratio (UACR) of ≥30 mg/g assessed by IRAE, IURAE or total AE concentrations was observed in 74, 273 and 417 participants, respectively. Among discordant pairs, there were 49 events in those classified as micro- and macroalbuminuric by IURAE, but normoalbuminuric by IRAE. Only the IRAE was a significant independent factor for the incidence of CV events [HR (95% confidence interval) 1.15 (1.04-1.27)]. The association of UAE with CV events was mainly driven by heart failure (HF) [HR 1.33 (1.15-1.55) for IRAE; HR 1.38 (1.06-1.79) for IURAE; HR 1.62 (1.22-2.13) for total AE]. Those subjects who were micro- and macroalbuminuric by both IRAE and IURAE had a significant increase in risk for any CV event, and especially for HF. CONCLUSIONS IRAE, IURAE and AE were associated with an increased risk for CV events, but IRAE offered better prognostic assessment.
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Affiliation(s)
- Fernando Martínez
- Internal Medicine Department, Clinical Hospital of Valencia, Valencia, Spain.,Area of Cardiometabolic and Renal Risk, Biomedical Research Institute Hospital Clinic of Valencia (INCLIVA), Valencia, Spain.,Department of Medicine, University of Valencia, Valencia, Spain
| | - Gernot Pichler
- Internal Medicine Department, Clinical Hospital of Valencia, Valencia, Spain.,Area of Cardiometabolic and Renal Risk, Biomedical Research Institute Hospital Clinic of Valencia (INCLIVA), Valencia, Spain
| | - Adrian Ruiz
- Internal Medicine Department, Clinical Hospital of Valencia, Valencia, Spain.,Area of Cardiometabolic and Renal Risk, Biomedical Research Institute Hospital Clinic of Valencia (INCLIVA), Valencia, Spain
| | | | - Felipe J Chaves
- Genetic and Genomic Unit, Research Institute of the Clinical Hospital of Valencia (INCLIVA), Valencia, Spain.,CIBER of Diabetes and Associated Metabolic Diseases (CIBERDEM), Institute of Health Carlos III, Madrid, Spain
| | - Veronica Gonzalez-Albert
- Genetic and Genomic Unit, Research Institute of the Clinical Hospital of Valencia (INCLIVA), Valencia, Spain
| | - Maria Tellez-Plaza
- Area of Cardiometabolic and Renal Risk, Biomedical Research Institute Hospital Clinic of Valencia (INCLIVA), Valencia, Spain.,Department of Environmental Health Sciences, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Hiddo J L Heerspink
- Department of Clinical Pharmacy and Pharmacology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Dick D E Zeeuw
- Department of Clinical Pharmacy and Pharmacology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Josep Redon
- Internal Medicine Department, Clinical Hospital of Valencia, Valencia, Spain.,Area of Cardiometabolic and Renal Risk, Biomedical Research Institute Hospital Clinic of Valencia (INCLIVA), Valencia, Spain.,Department of Medicine, University of Valencia, Valencia, Spain.,CIBER 03/06 Physiopathology of Obesity and Nutrition (CIBEROBN), Institute of Health Carlos III, Madrid, Spain
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Speeckaert MM, Speeckaert R, Van De Voorde L, Delanghe JR. Immunochemically unreactive albumin in urine: fiction or reality? Crit Rev Clin Lab Sci 2011; 48:87-96. [PMID: 21871001 DOI: 10.3109/10408363.2011.591366] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Urinary albumin measurements are currently not standardized due to a lack of a reference method and reference (primary and secondary [matrix]) material. Multiple molecular forms of albumin in urine are identified. Modification of albumin by proteolysis during passage through the urinary tract and chemical modification during specimen storage leads to the formation of albumin fragments. Multiple methods have been developed to quantify albuminuria and significant different results are reported dependent on the available assay. The current point of view of the National Kidney Disease Education Program - IFCC Working Group on Standardization of Albumin considers the immunoassay with polyclonal sera as the primary method of quantifying urine albumin. This article reviews the process of albumin fragmentation and focuses on the controversial topic of immuno-unreactive, nonimmunoreactive, or immunochemically nonreactive albumin fractions and its consequences for albumin analysis. We conclude that at present there are no hard arguments for measuring immunochemically unreactive albumin in urine. Immunoassays using polyclonal antisera for the detection of urinary albumin remain the gold standard. The development of a reference measurement procedure remains one of the challenges for the future.
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Affiliation(s)
- Marijn M Speeckaert
- Department of Clinical Chemistry, University of Ghent, Faculty of Medicine, Belgium
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Markó L, Szigeti N, Szabó Z, Böddi K, Takátsy A, Ludány A, Koszegi T, Molnár GA, Wittmann I. Potential urinary biomarkers of disease activity in Crohn's disease. Scand J Gastroenterol 2010; 45:1440-8. [PMID: 20653491 DOI: 10.3109/00365521.2010.505658] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
OBJECTIVE Measurement of the immunoreactive urinary albumin (ir-uAlb) concentration by immunological methods was found to be an effective method to identify disease activity in Crohn's disease (CD). Recently a size-exclusion (SE) high performance liquid chromatography (HPLC) method was developed to measure both ir-uAlb and non-immunoreactive urinary albumin (total, t-uAlb). We aimed to follow-up one of our CD patients with frequent remissions and exacerbation phases comparing the changes of disease activity parameters and the concentration of ir-uAlb and t-uAlb. The surprising results led us to perform measurements in greater depth. MATERIAL AND METHODS Concentration of ir-uAlb was measured by immunoturbidimetry (IT) and t-uAlb by SE-HPLC. Albumin peak of SE-HPLC was collected and applied to a reversed-phase (RP) HPLC and to gel-electrophoresis. Eluted peaks of RP-HPLC and identified bands of gel-electrophoresis were analyzed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS). RESULTS The concentration of t-uAlb was 15 times higher than that of the ir-uAlb during active state. The RP-HPLC and the gel-electrophoresis separation proved that albumin peak by size-exclusion consists of three different peaks. MALDI-TOF/MS measurements identified α1-acid-glycoprotein and Zn-α2-glycoprotein as major, and albumin as minor protein. CONCLUSIONS Peak of albumin of SE-HPLC contains a significant amount of glycoprotein during the active phase of CD, which could not be detected in remission. Urinary α1-acid-glycoprotein and/or Zn-α2-glycoprotein could be an ideal disease activity biomarker of CD.
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Affiliation(s)
- Lajos Markó
- 2nd Department of Medicine and Nephrological Center, University of Pécs, Faculty of Medicine, Pécs, Hungary
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