A Diagnostic Programme for Quantitative Analysis of Proteinuria

Abstract

Summary:A spectrum of quantitative methods was adapted to the Kone Specific Analyser for the purpose of recognizing, quantifying and differentiating various forms of proteinuria. Total protein, IgG, albumin and oci-microglobulin (measured by turbidimetry), N-acetyl-ß-.D-glucosaminidase activity and creatinine (measured photometrically), were measured in undiluted urine; in addition a r microglobulin was measured in serum.Within and between run predsion, accuracy and linearity of the turbidimetric methods were in good agreement with nephelometric procedures. All turbidimetric methods exhibited a correlation coefficient r > 0.98 when compared with the radial immunodiffusion procedure äs reference method. Total protein measured turbidimetrically with the Kone Specific Analyser was in good agreement with the manual biuret procedure.The low detection limits and linearities allowed quantification of urine analytes from the lower ränge of normals up to ten times the upper limit of normals.The measured analytes exhibited stability in urine at pH 4-8 over at least seven days at 4 -6 °C and -20 °C. Only IgG showed a significant loss (up to 30 percent), when measured after storage at -20 °C.Quantities per mol creatinine showed significantly lower intra-individual and inter-individual variability than quantities per liter. In 31 normal persons, the intraindividual Variation was lowest for N-acetyl-ß-Z>-glucosaminidase activity (13%) and highest for total protein (33%), when measured in the second morning urine on 5 consecutive days.When related to creatinine, resülts obtäined in the second morning urine showed no significant differences from those in 24 h urine, except for aj-microglobulin which gave lower values in 24 h urines.The upper normal limits, calculated äs the 95% ranges, were determined from 154 urines of 31 individuals. Nearly all analytes showed an asymmetric distribution. Because of a wide tailing of the upper limit, preliminary üpper normal limits were set aböve this ränge:Total protein: 7.9 g/mol creatinine (70 mg/g creatinine) IgG:1.13 g/mol creatinine (10 mg/g creatinine) Albumin:2.26 g/mol creatinine (20 mg/g creatinine) ocrMicroglobulin: " 1.58 g/mol creatinine (14 mg/g creatinine) N^Acetyl-ß-jD-glücosaminidäse: 0.56 kU/mol creatinine (5 U/g creatinine).Application of the newly adapted programme to unselected urines sent for urine analysis revealed a threefold incfease in the propörtion of resülts outside the normal ranges, compared with the routinely used protein test strip procedure. All additional positive urines exhibited either signs of glomerular or tubular proteinuria. Determination of albumin or N-acetyl-ß-jD-glucosaminidase excretion was sufficient to detect these additional cases.

Current Issues in Measurement and Reporting of Urinary Albumin Excretion

“…Interestingly, the CVi for the ACR or albumin concentration has not been examined carefully in random urine samples, but there are studies indicating a higher CVi in these settings (34,35; S1 and S14 in the online Data Supplement ). A second morning urine sample has been shown to be comparable to a 24-h sample (36 ), and 2 studies listed in Table S1 in the online Data Supplement that used second morning samples gave CVi values comparable to other studies that used first morning samples. However, no direct comparison between first and second Continued on page 27 We used PubMed to locate published clinical guidelines or recommendations that include urine protein measurement as a part of the assessment of kidney disease or as a risk factor for cardiovascular disease.…”

Renal Sorbitol, myo-Inositol and Glycerophosphorylcholine in Streptozotocin-Diabetic Rats

“…Creatinine was measured kinetically by the method of Jaffe adapted to the Kone Specific analyser (Kone, Turku, Finland) as described by Hofmann et al (19).…”

Symmetric dimethyl arginine and N-acetyl- β-D-glucosaminidase lysosimyria of proximal renal tubules as a target for nephrotoxicity in patients with rheumatoid arthritis treated with disease modifying antirheumatic drugs.

“…They can be useful in early diagnose of acute renal damage as nephrotoxicity caused by immunosuppressive drugs, contrast substances, antibiotics and cadmium exposition (3)(4)(5)(6)(7)(8)(9)(10). Urinary enzyme activity normally is very low in urine and is increased in renal tubular cell damage (11).…”