Measuring urinary IgG and IgG4 excretion

Kofoed‐Enevoldsen, Allan; Jensen, Karin; Beck, Thomas C.

doi:10.1093/clinchem/37.6.1136

Cited by 10 publications

(3 citation statements)

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“…Charge selectivity index was measured as IgG/IgG4 selectivity index, i. e. total IgG/IgG4 clearance ratio: clearance of IgG U -IgG/S -IgG = U -IgG x S -IgG4 clearance of IgG4 U -IgG4/S -IgG4 U -IgG4 x S -IgG in timed overnight urine samples (U = urine, S = serum). Serum and urine IgG and IgG4 concentrations were measured by enzyme linked immunosorbent assays as previously described [12,13], including pre-storage dilution of urine samples (1:5 in phosphate buffered saline supplemented with 1% bovine serum albumin). Samples were H.-J.…”

Section: Methodsmentioning

confidence: 99%

Glomerular charge selectivity and the influence of improved blood glucose control in Type 1 (insulin-dependent) diabetic patients with microalbuminuria

Bangstad¹,

Kofoed‐Enevoldsen²,

Dahl‐Jørgensen³

et al. 1992

Diabetologia

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We first compared glomerular charge selectivity index in two matched groups of Type 1 (insulin-dependent) diabetic patients with micro- and normoalbuminuria respectively, and secondly, investigated prospectively in a randomized clinical trial, the influence of improved metabolic control on selectivity index in diabetic patients with microalbuminuria. In Study 1, 27 patients with microalbuminuria (albumin excretion > or = 15 micrograms/min in at least two out of three overnight urine samples) were matched (age, diabetes duration, mean 1-year HbA1c, gender) with normoalbuminuria patients (n = 24), and in Study 2, 23 microalbuminuric patients were randomly allocated to either intensive (continuous subcutaneous insulin infusion) or conventional treatment. Glomerular charge selectivity index was measured as IgG/IgG4 selectivity index, i.e. total IgG/IgG4 clearance ratio in timed overnight urine samples. The microalbuminuric patients had a significantly reduced selectivity index compared to the normoalbuminuric patients: 1.20 (0.92-1.40) vs 1.68 (1.22-2.21), median and 95% confidence interval (p < 0.01). In Study 2, the HbA1c improved in the intensive-treatment group compared to the conventional-treatment group: at 2, 6 and 12 months the difference in mean percentage HbA1c between the groups was 1.1, 1.2 and 1.4, respectively (p < 0.01). A sharp 50% increment in IgG/IgG4 selectivity index was seen in the intensive-treatment group during the first 6 months (p < 0.05 compared to the conventional group). We conclude that adolescents and young adults in an early stage of diabetic nephropathy have reduced glomerular charge selectivity, which may be improved by reducing the mean blood glucose level.

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Section: Methodsmentioning

confidence: 99%

Glomerular charge selectivity and the influence of improved blood glucose control in Type 1 (insulin-dependent) diabetic patients with microalbuminuria

Bangstad¹,

Kofoed‐Enevoldsen²,

Dahl‐Jørgensen³

et al. 1992

Diabetologia

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“…Urine IgG, measured by ELISA, was not stable after 9 wk of −20°C storage in undiluted urine. 10 When measured by immunoturbidimetry, a significant decrease in uIgG was found after 6 mo of storage at −20°C. 23 Another study reported that uIgG, measured by nephelometry, decreased significantly during storage at −20°C, but remained stable during 2 y of −70°C storage.…”

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confidence: 96%

“…In humans, several studies investigated the stability of uIgG and uRBP during frozen storage. 9,10,15,21,23 Results of these studies are apparently conflicting yet hard to compare given differences in storage conditions and analytical methods. Urine IgG, measured by ELISA, was not stable after 9 wk of −20°C storage in undiluted urine.…”

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confidence: 99%

Stability of glomerular and tubular renal injury biomarkers in canine urine after 4 years of storage

et al. 2017

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The use of urine biomarkers to detect renal injury at an early stage is gaining interest in both human and veterinary medicine, 3,8,13,14,24 given that identification of early renal injury allows earlier therapeutic intervention. 17 The latter is hampered by the traditionally used diagnostic markers of decreased kidney function, serum creatinine and urea, as their concentration will only increase above the upper limit of the reference interval when >75% of nephrons are lost, making them insensitive markers for the detection of earlystage renal injury. 2,6 In contrast, urine biomarkers are generally accepted to be sensitive indicators of glomerular or tubular renal injury, and additionally have the capacity to quantify as well as localize this damage. 3,17 In research settings, enzyme-linked immunosorbent assays (ELISAs) are often used to detect and quantify biomarker proteins. Immunoassays of several glomerular and tubular biomarkers of renal injury, including immunoglobulin G (IgG) and C-reactive protein (CRP), respectively, as well as retinol-binding protein (RBP; Immunology Consultants Laboratory, Portland, OR), have been previously validated in our laboratory for use in canine urine.14 Consideration of preanalytical factors, such as sample handling and storage conditions, is important in order to perform reliable biomarker research. Because of prospective sampling, shipping, and performing analyses in batches, immediate analysis of fresh urine samples is impractical in most research settings. Therefore, storage of frozen samples for long periods (several months to years) is common. However, studies evaluating the stability of urine renal injury biomarkers during long-term storage are very scarce in veterinary medicine. Even in human medicine, relatively few studies have evaluated the impact of preanalytical factors on urine proteins. 4,7 To our knowledge, only a single urine biomarker study, investigating the stability of RBP, albumin, Abstract. Urine biomarkers are sensitive indicators of early-stage renal injury, consequently, research in this area is expanding in both human and veterinary medicine. However, studies investigating the impact of preanalytical factors, such as storage conditions, on urine biomarker concentrations are largely lacking in veterinary medicine. Therefore, we evaluated the stability of several renal injury biomarkers in canine urine after storage for 4 y at −72°C. Urine samples were collected from 26 dogs: 18 dogs with babesiosis and 8 healthy dogs. Concentrations of urine immunoglobulin G (uIgG), urine C-reactive protein (uCRP), and urine retinol-binding protein (uRBP) were measured, using validated commercial immunoassays, at the start of the study and 4 y later. To investigate the effect of long-term storage, absolute and relative differences between both measurements were compared. Additionally, dogs with babesiosis were compared with the healthy controls at both time points. Storage caused significant absolute and relative decreases in concentrations of all 3 biomarkers. Signi...

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Heparan sulphate in the pathogenesis of diabetic nephropathy

Kofoed‐Enevoldsen

1995

Diabetes Metab. Rev.

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Measuring urinary IgG and IgG4 excretion

Cited by 10 publications

References 0 publications

Glomerular charge selectivity and the influence of improved blood glucose control in Type 1 (insulin-dependent) diabetic patients with microalbuminuria

Glomerular charge selectivity and the influence of improved blood glucose control in Type 1 (insulin-dependent) diabetic patients with microalbuminuria

Stability of glomerular and tubular renal injury biomarkers in canine urine after 4 years of storage

Heparan sulphate in the pathogenesis of diabetic nephropathy

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