Evaluation of a particle-enhanced turbidimetric immunoassay for the measurement of ferritin: application to patients participating in an autologous blood transfusion program.

OBJECTIVES: To evaluate a turbidimetric immunoassay for the measurement of ferritin, and to assay this method in a group of patients undergoing an autologous blood transfusion program. DESIGN AND METHODS: We used an ILab 900 analyzer. This instrument automates a particle-enhanced immunoturbidimetric assay with an analysis time of 9 min. This technique was compared with a microparticle immunoassay. The turbidimetric assay was used to measure ferritin in a group of 30 patients undergoing an autologous blood transfusion program. RESULTS: The assay was linear in the range 3-1400 microg/L (r = 0.9999). The intra- and inter-assay imprecision (CV) at 20, 97 and 469 microg/L were <3.0 and <5.0%, respectively. Recovery was 88. 7 to 97.4%. The detection limit was 3 microg/L. Hemoglobin (

Hemorheological, coagulative and fibrinolytic changes during autologous blood donation.

BACKGROUND: Clinical data suggest that autologous blood donation may prevent postsurgical venous thrombosis. If confirmed, this is probably due to beneficial effects in rheologic and hematologic variables which may be changed in patients as a result of repeated bleeding. STUDY DESIGN AND METHODS: To ascertain this point, we studied variations in hematological, hemorheological, coagulative and fibrinolytic parameters in 30 patients undergoing autologous blood donation. RESULTS: Whole blood viscosity (WBV), plasma viscosity and blood viscosity adjusted to 40% hematocrit, progressively and substantially decreased throughout the successive bleeding at all the shear rates considered. WBV was further reduced by presurgical hemodilution with autologous plasma which decreased the platelet and leukocyte count. The hemostasis and fibrinolysis variables, however, underwent no clinically significative changes. CONCLUSION: Repeated bleedings change most hemorheological variables. By decreasing cytocrit and viscosity, reducing aggregability and increasing blood cell deformability an optimal milieu to help prevent thrombosis is artificially created.

Lipoprotein alterations in liver cirrhosis: a possible contribution to changes in plasma oncotic pressure and viscosity.

BACKGROUND/AIMS: To investigate whether physicochemical alterations in plasma lipoproteins are associated with changes in plasma oncotic pressure and viscosity in liver cirrhosis. METHODS: The study included 66 patients with cirrhosis (confirmed by liver biopsy) and 58 healthy volunteers. The constituents measured were: the concentration, density and composition of plasma lipoproteins; plasma oncotic pressure and viscosity; and the concentrations of albumin, total protein, haptoglobin, transferrin, immunoglobulin M and alpha2-macroglobulin. RESULTS: Step-wise multiple regression analysis indicated that, in the patients with cirrhosis, plasma oncotic pressure was significantly correlated with plasma albumin+viscosity (r=+0.85; p<0.001) and with plasma total protein+the density of low density lipoprotein (r=+0.74; p<0.001). The inclusion of viscosity and the density of low density lipoprotein in the regression equations significantly improved the observed correlation between albumin and plasma oncotic pressure (r=+0.70; p<0.001). Similarly, plasma viscosity was significantly correlated with the sum of plasma total protein and cholesterol (r=+0.68; p<0.001). The inclusion of cholesterol in the regression equation significantly increased the observed correlation between total protein and plasma viscosity (r=+0.59; p<0.001). CONCLUSIONS: These results suggest that lipoprotein alterations associated with liver cirrhosis may play a role in determining plasma oncotic pressure and viscosity, and thus could influence the progression of the disease.

Plasma protein abnormalities in nephrotic syndrome: effect on plasma colloid osmotic pressure and viscosity.

The concentrations of 25 plasma proteins were measured in 22 patients with membranous nephropathy. For some large proteins, the plasma concentrations were increased; there were also large proteins with low plasma concentrations, but small or medium-sized proteins showed uniformly lower plasma concentration than the controls. Plasma colloid osmotic pressure (pi) and viscosity (eta) were not interrelated but showed positive and significant correlations with plasma concentrations of small and medium-sized proteins (pi) and plasma concentrations of large proteins (eta), respectively. Nephrotic plasma is not efficient in maintaining plasma pi but highly efficient in maintaining plasma eta. High plasma fibrinogen concentrations and low antithrombin III concentrations may predispose to thrombosis, and low IgG concentrations may account for the higher predisposition to bacterial infection. The relative composition of nephrotic plasma is heavily dependent on the size of the different proteins. Plasma pi and eta are also maintained by the relative preponderance of different plasma proteins.

Effectiveness of very low doses of subcutaneous recombinant human erythropoietin in facilitating autologous blood donation before orthopedic surgery.

BACKGROUND: Clinical and pharmacokinetic data suggest that very low doses of subcutaneous recombinant human erythropoietin (rHuEPO) may be effective in a preoperative autologous blood deposit program. STUDY DESIGN AND METHODS: Fifty-two patients, scheduled for orthopedic surgery, were enrolled in a double-blind and placebo-controlled study. Patients were randomly assigned to the placebo group or to receive 30, 60, or 100 IU per kg of rHuEPO subcutaneously twice a week for 2 weeks before surgery. The dose of rHuEPO that was effective in facilitating the collection of 4 units of blood in the 2 weeks before surgery and that prevented a sharp decrease in hematocrit was determined. RESULTS: Only in patients receiving 100 IU per kg of rHuEPO did the outcome measurements differ significantly from those in the placebo group. With a higher (p < 0.01) cumulative increase in red cell volume during the study period (297 +/- 127 vs. 121 +/- 44 mL), 64 percent of those receiving 100 IU per kg of rHuEPO were able to donate 4 units of blood for autologous use, as compared with 23 percent of the placebo group (p < 0.05). Allogeneic transfusion was avoided, and the preoperative hematocrit and reticulocyte count were significantly higher in the patients receiving 100 IU per kg of rHuEPO (p < 0.05 and p < 0.01, respectively). CONCLUSION: Subcutaneously administered rHuEPO at a dose of 100 IU per kg twice a week for 2 weeks is effective in facilitating the collection of blood for autologous use and may improve the cost-benefit ratio of blood conservation interventions. Doses < or = 60 IU per kg are ineffective in facilitating such collections in this surgical setting.

Automated latex agglutination immunoassay of serum ferritin with a centrifugal analyzer.

A considerable demand for convenient, rapid, inexpensive assays of ferritin in serum has been generated in recent years in hospital laboratories and blood banks. We describe a simple and rapid particle-enhanced turbidimetric immunoassay suitable for routine application in a Monarch 2000 centrifugal analyzer with commercially available reagents. This fully automated assay (y) requires no pretreatment of sample, and correlation with a two-step sandwich ELISA (x) is excellent (y = 1.018x + 0.397, Sy/x = 0.027). The analytical range extends from 5 to 900 micrograms/L. Intraassay imprecision (CV) ranged from 1.1% to 5% for various specimen concentrations. Interassay imprecision ranged from 2.2% for above-normal concentrations (755 micrograms/L) to 9.5% for low concentrations (39 micrograms/L). No specimen-related carryover was detected. The method has been useful in our predeposit autologous blood transfusion program for rapid assessment of iron status in patients undergoing repeated phlebotomies.