March 28, 2008
To: Chiefs of Service, Attending Physicians, Housestaff, Nurses and Other Concerned Personnel
From: Eberhard Fiebig, MD
Director, Clinical Laboratory and Division Chief, Hematology
Re: Hematology Testing Updates: D-Dimer and Reticulocyte Hemoglobin Content (CHR)______
1. Change in D-dimer Reportable Range
Effective Apri1 1, 2008 the Clinical Laboratory is lowering the upper end of the reportable range for D-dimer testing from 10,000 to 4,000 ng/mL FEU; i.e., values exceeding the new cut-off will be reported as > 4,000 ng/mL. This will obviate the need to perform repeat testing on diluted samples for D-dimer values between 4,000 - 10,000 ng/mL, resulting in faster turn-around-times and cost savings.
If it is mandatory for patient management to quantitate D-dimers in the 4,000-10,000 ng/mL FEU range, this can be done upon special request (please indicate on the laboratory requisition or electronic order or contact the Hematology Laboratory at 206-8582).
2. New Test for Early Iron Deficiency: Reticulocyte Hemoglobin Content (CHR)
Reticulocyte hemoglobin content (CHR) is measured flow cytometrically on the ADVIA 2120 hematology analyzer. It represents the hemoglobin content in reticulocytes, the youngest circulating red blood cells (RBC), which transition to mature RBC in 1 to 2 days. As such, CHR can be helpful in identifying iron deficiency states, including “functional” iron deficiency earlier than traditional tests for this condition. Specifically, CHR has been found useful in screening infants 9–12 months old for iron deficiency anemia (Ulrich et al. JAMA 2005; 294:924-930), and in monitoring patient response to iron and erythropoietin therapies in hemodialysis patients (Fishbane et al. Kidney Int 2001; 60:2406-2411).
Specimen requirements for CHR are the same as for CBC; i.e., minimum 1 mL blood specimen collected in K2 EDTA, “lavender top tube.” The test is available 24 hrs/7 days, and may be ordered in conjunction with CBC and reticulocyte testing or by itself. Please order “CHR” electronically or by writing “reticulocyte hemoglobin content” on the Clinical Laboratory requisition (a check box for CHR will be added at the next revision of the requisition).
Reticulocyte Hemoglobin Content (CHR) Reference Ranges:
Age / Male (pg/cell) / Female (pg/cell)1 day – < 2 years / 22.5 - 31.8 / 23.9 - 30.9
2 years – < 6 years / 25.1 - 32.0 / 26.4 - 32.1
6 years – < 12 years / 23.6 - 33.9 / 25.1 - 33.3
12 years – 18 years / 27.0 - 33.2 / 28.2 - 33.9
18 years and older / 30.1 - 34.6 / 27.1 - 35.2
adapted from Soldin et al. Pediatric Reference Intervals, 5th ed. AACC Press Washington, DC, 2003.
For questions please contact the Hematology / Blood Bank Laboratory Medicine Resident (206-5689 or pager 650-997-9952) or Dr. Eberhard Fiebig (206-8588).