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Analysis of urinary proteins by SDS-agarose gel electrophoresis in multiple myeloma patients
44TH ANNUAL CSCC-CAMB-AACC CONFERENCE
than 0.5 L/minute. The differences between the two results were not clinically significant; only one patient was positive. Conclusion: Our results suggest that either the assessment of sweat rate may have been inaccurate or that the sweat rate is not very critical. Errors in assessing the sweat rate may be due to late onset of sweating, tiring of sweat glands, or a loss of volume due to dead space. Given the enormous implications of this diagnosis, it is important that standardised procedures be followed to achieve both an accurate sweat collection and analysis. 21 ANALYSIS OF URINARY PROTEINS BY SDSAGAROSE GEL ELECTROPHORESIS IN MULTIPLE MYELOMA PATIENTS Le Bricon, T. , Benlakehal, M., and Bousquet, B. Laboratoire de Biochimie A, Hoˆpital St-Louis, 75010 Paris, France Objectives: SDS-agarose gel electrophoresis is a new technique which separates proteins according to their molecular weight (1). The usefulness of this technique has not been fully established for the routine laboratory analysis of proteinuria in myeloma patients. Methods: We consecutively evaluated 95 hospitalized patients (50H/45F, 60 ⫾ 11 years, serum monoclonal fraction: 30 ⫾ 19 g/L). Electrophoresis of urinary proteins was realized using the Hydragel prote´inurie威 kit (Sebia). Screening for total urinary protein was performed with the MultistixR strips (Bayer) followed by a pyrogallol red determination (Hitachi 747, Boehringer). Results: Total proteinuria ranged from 0.04 to 19.04 g/24h and was within normal range in 33% of patients (⬍0.15 g/24h). Urinary monoclonal light chains were detected in 61% of patients; 24h excretion varied from 0.04 to 18.2 g (by densitometric scanning of the gel). Seventy % of patients had an urinary profile by SDS-agarose gel electrophoresis suggesting an impaired renal function, more frequently of the glomerular type (67%), then tubular (28%) and mixed (5%). Light chain excretion was significantly associated with higher total proteinuria (KruskalWallis, p ⬍ 0.0001), discordance between strips and red pyrogallol protein measurements (khi2, p ⬍ 0.0001) and the presence of an abnormal urinary protein profile (p ⬍ 0.01). Conclusions: Evaluation of urinary proteins by SDSagarose gelelectrophoresis allows easy follow-up of light chain excretion (disease activity, therapeutic efficacy) and renal function in myeloma patients. Reference: 1. Clin Chem 1998; 44: 1191–7. 22 PLASMA CYSTATIN C: A BETTER MARKER OF GLOMERULAR FILTRATION RATE THAN CREATININE IN KIDNEY TRANSPLANTATION Le Bricon, T.,1 Thervet, E.,2 Froissart, M.,3 Benlakehal, M.,1 Bousquet, B.,1 Legendre, C.,2 and Erlich, D.4 Laboratoire de Biochimie A1, Service de Nephrologie2, Service de Physiologie3 (Hoˆpital Broussais), Laboratoire de Biochimie B4, Hoˆpital St-Louis, Av. Claude Vellefaux, 75010 Paris, France 232
Objectives: Plasma cystatin C is a more sensitive marker of acute changes in glomerular filtration rate (GFR) than creatinine in kidney transplant recipients (1). Long-term follow-up of renal function by cystatin C has not been yet investigated. Methods: GFR was measured in 25 patients (44 ⫾ 9 years, M/F: n ⫽ 11/14) 3 months after surgery by the 51Crlabeled EDTA. Cystatin C was measured by immunonephelometry (BN100, Dade-Behring) and creatinine by the Jaffe´ reaction (Hitachi 747, Boehringer). Their accuracy to estimate GFR was calculated from the relative increase in their concentration vs. their upper normal limits and the decrease in 51Cr-EDTA clearance vs. the lower limit of 80 mL/min/1.73m2. Statistical analysis was performed by linear regression and Kruskal-Wallis test (p ⬍ 0.05). Results: 51Cr-EDTA clearance ranged from 31 to 97 mL/ min/1.73m. The reciprocal of plasma creatinine correlated with 51Cr-EDTA clearance (r ⫽ 0.784, p ⬍ 0.0001). Plasma creatinine significantly overestimated GFR by 30% (7 false negatives). The reciprocal of plasma cystatin C correlated with 51Cr-EDTA clearance (r ⫽ 0.879, p ⬍ 0.0001): GFR (mL/min/1.73m) ⫽ 78 ⫻ (1/cystatin C in mg/L) ⫹ 4. Cystatin C significantly underestimated GFR by 15% with no false negatives. Conclusions: Plasma cystatin C appears superior to creatinine for evaluation of renal function in kidney transplanted patients. GFR can be rapidly estimated from plasma cystatin C using a formula independent of age, body surface and sex of the recipient. Reference: 1. Clin Chem 1999; 45: 2243–9. 23 CEA VITROS ECI ASSAY COMPARED TO FOUR COMMONLY USED METHODS Leclerc, P.,1 Gignac, S.,1 Massé, J.,2 Fruteau de Laclos, B.,1 Nadeau, L.1 and Turcotte, G.1 Service de biochimie1, CHAU de Que´bec, 1050, ch. Sainte-Foy, Que´bec, Canada G1S 4L8 and Service de biochimie2, CHU de Que´bec, 2705, boul. Laurier, Sainte-Foy, Canada G1V 4J2 CEA is measured on the Vitros ECi Immunodiagnostic System (Ortho-Clinical Diagnostics) with an immunometric technique involving a biotinylated antibody and a horseradish peroxidase-labeled antibody conjugate. Both antibodies are mouse monoclonal anti-CEA. The conjugate bound to streptavidin-coated wells is measured by a luminescent reaction. Objective: To compare the ECi assay to four other methods: DPC Coat-A-Count IRMA, Bayer Immuno 1, Abbott Axsym and Beckman Access. Methods: We selected 80 samples (range 0 to 1400 g/L) and measured (within one calibration except for IRMA) CEA levels with each method (76 samples on the Access). We used Passing & Bablok regression (ECi ⫽ y) to calculate slope and intercept, least squares regression for r and sy/x and Wilcoxon signed rank test to compare mean values for samples within the reference range (ⱕ 5 g/L) (n ⫽ 24). CLINICAL BIOCHEMISTRY, VOLUME 33, APRIL 2000
than 0.5 L/minute. The differences between the two results were not clinically significant; only one patient was positive. Conclusion: Our results suggest that either the assessment of sweat rate may have been inaccurate or that the sweat rate is not very critical. Errors in assessing the sweat rate may be due to late onset of sweating, tiring of sweat glands, or a loss of volume due to dead space. Given the enormous implications of this diagnosis, it is important that standardised procedures be followed to achieve both an accurate sweat collection and analysis. 21 ANALYSIS OF URINARY PROTEINS BY SDSAGAROSE GEL ELECTROPHORESIS IN MULTIPLE MYELOMA PATIENTS Le Bricon, T. , Benlakehal, M., and Bousquet, B. Laboratoire de Biochimie A, Hoˆpital St-Louis, 75010 Paris, France Objectives: SDS-agarose gel electrophoresis is a new technique which separates proteins according to their molecular weight (1). The usefulness of this technique has not been fully established for the routine laboratory analysis of proteinuria in myeloma patients. Methods: We consecutively evaluated 95 hospitalized patients (50H/45F, 60 ⫾ 11 years, serum monoclonal fraction: 30 ⫾ 19 g/L). Electrophoresis of urinary proteins was realized using the Hydragel prote´inurie威 kit (Sebia). Screening for total urinary protein was performed with the MultistixR strips (Bayer) followed by a pyrogallol red determination (Hitachi 747, Boehringer). Results: Total proteinuria ranged from 0.04 to 19.04 g/24h and was within normal range in 33% of patients (⬍0.15 g/24h). Urinary monoclonal light chains were detected in 61% of patients; 24h excretion varied from 0.04 to 18.2 g (by densitometric scanning of the gel). Seventy % of patients had an urinary profile by SDS-agarose gel electrophoresis suggesting an impaired renal function, more frequently of the glomerular type (67%), then tubular (28%) and mixed (5%). Light chain excretion was significantly associated with higher total proteinuria (KruskalWallis, p ⬍ 0.0001), discordance between strips and red pyrogallol protein measurements (khi2, p ⬍ 0.0001) and the presence of an abnormal urinary protein profile (p ⬍ 0.01). Conclusions: Evaluation of urinary proteins by SDSagarose gelelectrophoresis allows easy follow-up of light chain excretion (disease activity, therapeutic efficacy) and renal function in myeloma patients. Reference: 1. Clin Chem 1998; 44: 1191–7. 22 PLASMA CYSTATIN C: A BETTER MARKER OF GLOMERULAR FILTRATION RATE THAN CREATININE IN KIDNEY TRANSPLANTATION Le Bricon, T.,1 Thervet, E.,2 Froissart, M.,3 Benlakehal, M.,1 Bousquet, B.,1 Legendre, C.,2 and Erlich, D.4 Laboratoire de Biochimie A1, Service de Nephrologie2, Service de Physiologie3 (Hoˆpital Broussais), Laboratoire de Biochimie B4, Hoˆpital St-Louis, Av. Claude Vellefaux, 75010 Paris, France 232
Objectives: Plasma cystatin C is a more sensitive marker of acute changes in glomerular filtration rate (GFR) than creatinine in kidney transplant recipients (1). Long-term follow-up of renal function by cystatin C has not been yet investigated. Methods: GFR was measured in 25 patients (44 ⫾ 9 years, M/F: n ⫽ 11/14) 3 months after surgery by the 51Crlabeled EDTA. Cystatin C was measured by immunonephelometry (BN100, Dade-Behring) and creatinine by the Jaffe´ reaction (Hitachi 747, Boehringer). Their accuracy to estimate GFR was calculated from the relative increase in their concentration vs. their upper normal limits and the decrease in 51Cr-EDTA clearance vs. the lower limit of 80 mL/min/1.73m2. Statistical analysis was performed by linear regression and Kruskal-Wallis test (p ⬍ 0.05). Results: 51Cr-EDTA clearance ranged from 31 to 97 mL/ min/1.73m. The reciprocal of plasma creatinine correlated with 51Cr-EDTA clearance (r ⫽ 0.784, p ⬍ 0.0001). Plasma creatinine significantly overestimated GFR by 30% (7 false negatives). The reciprocal of plasma cystatin C correlated with 51Cr-EDTA clearance (r ⫽ 0.879, p ⬍ 0.0001): GFR (mL/min/1.73m) ⫽ 78 ⫻ (1/cystatin C in mg/L) ⫹ 4. Cystatin C significantly underestimated GFR by 15% with no false negatives. Conclusions: Plasma cystatin C appears superior to creatinine for evaluation of renal function in kidney transplanted patients. GFR can be rapidly estimated from plasma cystatin C using a formula independent of age, body surface and sex of the recipient. Reference: 1. Clin Chem 1999; 45: 2243–9. 23 CEA VITROS ECI ASSAY COMPARED TO FOUR COMMONLY USED METHODS Leclerc, P.,1 Gignac, S.,1 Massé, J.,2 Fruteau de Laclos, B.,1 Nadeau, L.1 and Turcotte, G.1 Service de biochimie1, CHAU de Que´bec, 1050, ch. Sainte-Foy, Que´bec, Canada G1S 4L8 and Service de biochimie2, CHU de Que´bec, 2705, boul. Laurier, Sainte-Foy, Canada G1V 4J2 CEA is measured on the Vitros ECi Immunodiagnostic System (Ortho-Clinical Diagnostics) with an immunometric technique involving a biotinylated antibody and a horseradish peroxidase-labeled antibody conjugate. Both antibodies are mouse monoclonal anti-CEA. The conjugate bound to streptavidin-coated wells is measured by a luminescent reaction. Objective: To compare the ECi assay to four other methods: DPC Coat-A-Count IRMA, Bayer Immuno 1, Abbott Axsym and Beckman Access. Methods: We selected 80 samples (range 0 to 1400 g/L) and measured (within one calibration except for IRMA) CEA levels with each method (76 samples on the Access). We used Passing & Bablok regression (ECi ⫽ y) to calculate slope and intercept, least squares regression for r and sy/x and Wilcoxon signed rank test to compare mean values for samples within the reference range (ⱕ 5 g/L) (n ⫽ 24). CLINICAL BIOCHEMISTRY, VOLUME 33, APRIL 2000