Laser immunonephelometry for routine quantification of urinary albumin excretion.

Abstract

We describe a laser-immunonephelometric method for quantifying urinary albumin excretion (UAE) in large numbers of samples. For a 150-microL sample incubated at room temperature for 45 min with 40 microL of antiserum specific for human serum albumin, the assay range for albumin was 0.34 to 43.0 mg/L. For samples analyzed undiluted and diluted 10-fold, the range of measurable albumin was from 0.34 to 430.0 mg/L. With an automated version of this method, one can assay 240 samples per hour. Intra- and interassay CVs were less than 6% and 9%, respectively. Measurements by this method (y) correlated well with those obtained by a RIA method (x): y = 1.00x + 0.163 mg/L (n = 233; r = 0.996). The day-to-day CV for UAE was determined for three consecutive determinations done on each of 60 controls according to the time of collection and in 212 diabetics according to the amount of 24-h UAE. For controls, UAE was 8.0 +/- 8.1 mg/24 h (mean +/- SD), CV 44 +/- 23%. The CV was similar for diurnal (50 +/- 28%) and overnight (58 +/- 32%) collections from controls; and for diabetics with normal values for UAE: 35 +/- 32%, with slight albuminuria (25-300 mg/24 h):37 +/- 28%, or with macroalbuminuria (greater than 300 mg/24 h): 47 +/- 42%.

Plasma proprotein‐convertase‐subtilisin/kexin type 9 (PCSK9) and cardiovascular events in type 2 diabetes

“…UAE was measured by nephelometry. 21 In addition, in the DIABHYCAR study, high-sensitivity C-reactive protein (hsCRP) concentrations were determined by turbidimetry using a high-sensitivity commercial kit (Hitachi 911; Boehringer Mannheim, Mannheim, Germany).…”

Evaluation of the Behring Nephelometer for Detection of Low Level Urinary Albumin

“…This new instrument offers the advantage of a considerably shorter incubation time when compared with methods previously reported. 13 Furthermore, the current method allows for urinary specimen analysis without prior manual predilution, minimizing the inherent random error thus introduced. Preanalytical specimen centrifugation appears to be a requirement for analysis of undiluted specimens.…”

“…6 Many techniques exist to detect subclinical albuminuria, including radial immunodiffusion, 22 radioimmunoassay, 23 enzyme immunoassay, 16 dye binding assays (nonspecific proteinuria), 18 and immunonephelometric and immunoturbidimetric procedures. 13,21 Most reported techniques are either imprecise or relatively time consuming. Nephelometry offers the advantage of acceptable precision, possibility for automation, and ease of analysis.…”

“…An immunonephelometric assay using the Behring Laser Nephelometer recently was reported, offering excellent precision and semiautomatic operation. 13 Urinary albumin determination using the new Behring Nephelometer has been briefly reported by Behring Diagnostics and collaborators in Europe. 5,12 This study reviews our findings, compares them with those from Europe, and discusses modifications we have made to the standard protocols that facilitate analysis.…”

Excretion of Urinary Protein Induced by Extracorporeal Piezoelectric Lithotripsy

“…We used IgG and albumin to monitor glomerular function and NAG and lysozyme in order to determine tubular function. Quantification of urinary albumin excretion (Magnotti et al, 1989) is often used for the early assessment of lesions of the glomerulus in pathological conditions such as essential hypertension (Marre et al, 1987), kidney rejection after renal transplantation or different forms of diabetes (Watts et al, 1986). NAG, a high molecular mass lysosomal enzyme (MW 140,000) mainly present in the proximal convoluted tubule (Stolarek et al, 1989) is an extremely sensitive index of renal parenchymal damage, a reliable tool for monitoring kidney disease and an early indicator of immune rejection in patients with renal allografts (Horak et al, 1981).…”