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UNSATURATED IRON BINDING CAPACITY
This procedure is valid for the following chemistry analyzers:
Iron (non-heme) measurements are used in the diagnosis and treatment of diseases such as iron deficiency anemia, hemochromatosis (a disease associated with widespread deposit in the tissues of two iron-containing pigments, hemosiderin and hemofuscin, and characterized by pigmentation of the skin), and chronic renal disease. Transferrin is the major iron carrying protein in the serum.
Serum iron concentration connotes the Fe (III) bound to serum transferrin and does not include the iron contained in serum as free hemoglobin. Because normally only about one third of the iron binding sites of transferrin are occupied by Fe (III), serum transferrin has considerable reserve Iron Binding Capacity. This is called the serum Unsaturated Iron Binding Capacity (UIBC).1
System reagent for the quantitative determination of Unsaturated Iron Binding Capacity (UIBC) in human serum or plasma on Beckman Coulter AU Clinical Chemistry analyzers.
In the Beckman Coulter AU System UIBC procedure, ferrous-Iron (Fe2+) at alkaline pH, added to serum, binds specifically with transferrin at unsaturated iron binding sites. Remaining unbound ferrous iron reacts with the Nitroso-PSAP [2-Nitroso-5-(N-propyl-N-sulfopropylamino)phenol] to form an intense green complex. The difference between the resulting change in the measured absorbance and the absorbance from the total amount added to serum is equivalent to the quantity bound to transferrin. This is the Unsaturated Iron Binding Capacity (UIBC).
Samples should be taken in the morning from patients in a fasting state, since iron values can decrease by 30% during the course of the day.2
Serum or heparinized plasma samples, free from hemolysis, are the recommended specimens. Remove serum from the red cells to minimize hemolysis. Plasma specimens collected with EDTA, oxalate, or citrate are not recommended, since they bind iron, preventing its reaction with the chromogen.2
Serum iron is stable for 7 days at 2 - 8C or 4 days at room temperature (15 - 25C) after the serum is separated from red cells.2
EQUIPMENT AND MATERIALS:
Beckman Coulter AU400/AU400e, AU480, AU600, AU640/AU640e, AU680, AU2700, AU5400 and AU5800 analyzers.
Beckman Coulter AU System Unsaturated Iron Binding Capacity Reagent
Final concentration of reactive ingredients:
Also contains preservatives.
Test tubes 12 -16 mm in diameter or sample cups (Cat No. AU1063).
Beckman Coulter Chemistry Calibrator (Cat. No. DR0070)
1. UIBC R1: Pour an aliquot of R1 buffer into R1a bottle and mix gently by inversion. Pour entire contents of R1a into R1 bottle and mix gently by inversion. Repeat this process once more.
Note: It is important that the entire contents of the R2a color reagent be transferred to R2 and thoroughly mixed. Failure to do so may result in high bottle to bottle imprecision of control and patient recovery.
The Beckman Coulter Chemistry Calibrator reconstitution:
1. The unopened reagents are stable until the expiration date printed on the label when stored at 2 - 8°C.
2. Working reagents are stable for 30 days when stored in the refrigerated compartment of the analyzer.
Indications of Deterioration:
Discoloration of the reagent, visible signs of microbial growth, turbidity or precipitation in reagent may indicate degradation and warrant discontinuance of use.
The following data was obtained using this UIBC Reagent on Beckman Coulter AU analyzers according to established procedures. Results obtained at individual facilities may differ.
Estimates of precision, based on CLSI recommendations6, are consistent with typical performance. The within run precision is less than 8%CV and total precision is less than 10%CV. Assays of serum pools and control sera were performed and the data reduced following CLSI guidelines.
Patient samples were used to compare this UIBC Reagent. Representative performance data on AU analyzers is shown in the next table.
The typical change in absorbance for 1 µg/dL of UIBC is 0.32 mAbsorbance.
Perform a one-point calibration (AB) using a water blank (blue rack) and the appropriate calibrator in a yellow calibration rack. The frequency of calibration for the Unsaturated Iron Binding Capacity procedure is every 14 days. Calibration of this Unsaturated Iron Binding Capacity procedure is accomplished by use of Beckman Chemistry Calibrator (Cat No. DR0070).
Recalibration of this test is required when any of these conditions exist:
3. A critical part was replaced.
During operation of the Beckman Coulter AU analyzer at least two levels of an appropriate quality control material should be tested a minimum of once a day. In addition, controls should be performed after calibration, with each new lot of reagents, and after specific maintenance or troubleshooting steps described in the appropriate AU User’s Guide. Quality control testing should be performed in accordance with regulatory requirements and each laboratory’s standard procedure.
A complete list of test parameters and operating procedures can be found in the appropriate User’s Guide and at www.beckmancoulter.com.
For SI units (umol/L), multiply the results by 0.1786.
Adults5: 155 - 355 µg/dL
Expected values may vary with age, sex, diet and geographical location. Each laboratory should determine its own expected values as dictated by good laboratory practice.
Procedures for Abnormal Results:
Abnormal results are flagged by the listed analyzers according to the normal values entered by the user into the instrument parameters.
Results are automatically printed for each sample in mg/dL at 37°C.
The Beckman Coulter AU System Unsaturated Iron Binding Capacity procedure is linear from 55 - 450 µg/dL. Samples exceeding the upper limit of linearity should be diluted and repeated. The sample may be diluted, repeated and multiplied by the dilution factor automatically utilizing the AUTO REPEAT RUN.
Results of studies3 show that the following substances interfere with this UIBC procedure.
The criteria for no significant interference is recovery within 10% of the initial value.
* Intralipid, manufactured by KabiVitrium Inc., is a 20% IV fat emulsion used to emulate extremely turbid samples.
The information presented is based on results from Beckman Coulter studies and is current at the date of publication. Beckman Coulter Inc., makes no representation about the completeness or accuracy of results generated by future studies. For further information on interfering substances, refer to Young4 for a compilation of reported interferences with this test.
1. Burtis, C.A. and Ashwood, E.R., Tietz Textbook of Clinical Chemistry, Second Edition, W.B. Saunders Co., 1994.
2. Perrotta, G., Iron and Iron-Binding Capacity, In: Pesce, A.J., Kaplan, L.A. editors., Methods in Clinical Chemistry, C.V. Mosby, St. Louis, 1258 - 1261, 1987.
3. CLSI/NCCLS, Interference Testing in Clinical Chemistry, EP7-A2, 2005.
4. Young, D.S., Effects of Drugs on Clinical Laboratory Tests, Fifth Edition, Washington, DC, AACC Press, 2000.
5. Beckman Coulter Inc. data on samples collected from 200 blood donors in North Texas.
6. CLSI/NCCLS Evaluation Protocol EP5 - A2, 2004.
7. Data on file for specific AU analyzers.
© Beckman Coulter, Inc. March 2012 CLSIOSR6x205.02
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