Abstract: SA-PO097

Clinical Consequences of Different Albumin Measurement Methods in Patients with Membranous Nephropathy

Session Information

Category: Glomerular

  • 1005 Clinical Glomerular Disorders

Authors

  • Vink- van Setten, Coralien, Radboud UMC, Nijmegen, Netherlands
  • van de Logt, Anne-Els, Radboud UMC, Nijmegen, Netherlands
  • Wetzels, Jack F., Radboud University Medical Center, Nijmegen, Netherlands
Background

Albumin levels are often used to define disease or predict risk. Cut off values are used to define nephrotic syndrome or advise toward the use of prophylactic anticoagulant therapy in patients with membranous nephropathy (MN). However, differences between albumin assays, although recognized (Bachmann 2016) are often unnoticed. In this study we aimed at quantifying differences between different albumin assays (immunonephelometry (reference), bromcresol green (BCG) and bromcresol purple (BCP)) in nephrotic patients with MN.

Methods

Plasma samples were collected from nephrotic patients with MN. Samples were stored at -80 °C. Albumin was measured with BCG, BCP and immunonephelometry in plasma in our hospital. A round robin was organized to compare the results of the BCG assay used in three regional hospitals.

Results

We included 23 MN patients (83% male), mean age was 60 ± 13 years, median serum creatinine level was 107 µmol/l (IQR 83-152) and median protein creatinine ratio 6.3 g/10 mmol (IQR 3.9-8.9). Mean serum albumin in nephelometric assay was 21.1±4.5 g/l. Whereas bias with the BCP was limited (0.3±1.8 g/l), BCG reported higher bias (5.1±1.9 g/l). Three regional hospitals, that used BCG, also reported higher serum albumin values. Variation between centers was large (Figure 1). Bias in hospital 1 and 3 was very high; respectively 6.7±2.1 g/l and 7.7±2.3 g/l. In hospital 2 a bias comparable with our assay (4.8±1.9 g/l) was noticed. Calculated accuracy of prophylactic anticoagulant therapy using a cut-off value of 25 g/l ranged between 53 % and 83 %, indicating that up to 47 % of patients might not receive appropriate therapy.

Conclusion

A large bias and impression was noticed between different albumin assays in patients with MN. The BCG assay overestimates serum albumin values. There were large between-centers differences. Inaccuracy of serum albumin assays will contribute to incorrect treatment decision. Clinicians should be aware of these variations. More attention to calibration and standardization is urgently needed.

Funding

  • Government Support - Non-U.S.