DaVita Study Demonstrates Clinical Application Of Sysmex Reticulocyte Hemoglobin Equivalent (RET-He) Parameter

Main Category: Urology / Nephrology
Also Included In: Blood / Hematology;  Clinical Trials / Drug Trials
Article Date: 11 Jun 2009 - 4:00 PDT

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Sysmex America, Inc. announced that a study titled "Day-to-Day, Week-to-Week, and Day-of-the-Week Variations in Tests of Anemia and Iron Status in Hemodialysis Patients" has identified Sysmex's Reticulocyte Hemoglobin Equivalent (RET-He) parameter result as key input used by physicians to assist in Anemia treatment decisions in ESRD patients on hemodialysis. David Van Wyck, M.D., Vice President of Clinical Affairs at DaVita Inc., and Emeritus Professor of Medicine and Surgery at the University of Arizona College of Medicine, in Tucson et. al followed five hematologic parameters in 30 patients undergoing hemodialysis three times a week. The patients were followed for 12 consecutive treatment days. The parameters studied were Hb, Hct, reticulocyte Hb (RET He or CHr), TSAT and ferritin levels.

The purpose of the DaVita(R) study was to evaluate the clinical value of these five parameters for supporting the physician's ability to make informed dosing decisions for ESA and IV iron therapy.

According to Dr. Van Wyck, "It has been difficult to know if the observed variability is within the 'expected ranges' for these patients or if changes in these markers signify a trend. Prior to this study, little information was available on expected day-to-day, within-patient variability among patients undergoing dialysis."

Over the course of the study, ESA doses were held constant and IV iron therapy was withheld. Same-sample analytic variability was measured, as was within-patient "biologic" variability. The number of sampling days needed to determine the true average value for each analyte was calculated with a 5% significance level and an 80% level of accuracy.

For all five parameters, "biologic" variation exceeded analytic variation, particularly for TSAT and ferritin. Hb and Hct were affected by the day of the week blood was drawn, with Hb levels averaging 0.06g/dL higher midweek versus those obtained the first dialysis day of the week. Hb, Hct and Ret-He/CHr values were measured using a Sysmex XE-2100 instrument.

The authors concluded that because of the high "biologic" variation observed, multiple test days are needed to achieve clinically meaningful accuracy and that HB, Hct and reticulocyte Hb (Ret-He or CHr) were useful analytes to guide ESA and IV iron therapy, whereas ferritin and TSAT were not reliable guides for month to month dose adjustments for ESA or IV iron. They may, however, be useful for assessing iron status or setting broad therapeutic targets in large patient populations. Day of the week effects are minimal for HB and Hct, and undetectable for other analytes.

"The advantages inherent in directly assessing immature cells are potentially under-recognized. The publication of this study supports our belief that the advantages of direct cellular analysis versus indirect assumptions on iron status [storage or transport protein measurement, serum iron, or algorithms] may well be a means of refining complex anemia treatment decisions," said Ian Giles, M.D., Director of Scientific Affairs, Sysmex America, Inc.

The study poster was presented at the recent 2009 National Kidney Foundation Spring Clinical Meeting held in Nashville, TN and attended by nearly 2,500 attendees including physicians, fellows and residents, physician assistants, nurse practitioners, nurses and technicians, renal and clinical dietitians, and social workers.

DaVita is a registered trademark of DaVita Inc. All other trademarks are the property of their respective owners.

About RET-He

RET-He is an established parameter in the National Kidney Foundation's KDOQI (Kidney Disease Outcomes Quality Initiative) guidelines for assessing the initial iron status of patients with chronic kidney disease on hemodialysis as well as IV iron replacement in these patients. The Sysmex XE-5000, XE-2100 and the XT-2000i Automated Hematology Analyzers provide the RET-He parameter, which quantifies the hemoglobin content of reticulocytes. Sysmex technology uses proprietary polymethine dyes that have an affinity to, and fluorescently label, nucleic acids. Detection and characterization of immature cells may well be a more valuable approach than measuring storage or transport proteins, serum iron, or algorithms which incorporate indirect assumptions.

About Sysmex America, Inc.

Sysmex America, Inc., the U.S. headquarters of Sysmex Corporation (Kobe, Japan), is a world leader in clinical laboratory systemization and solutions, including clinical diagnostics, automation and information systems. Serving customers for over 40 years, Sysmex focuses on extending the boundaries of diagnostic science while providing the management information tools that make a real difference in clinical and operational results for people worldwide.

Source: Sysmex America