Measurement uncertainty in tests used to evaluate iron deficiency anemia

Aim: Measurement uncertainty is a parameter associated with the result of measurement, that characterises the dispersion of values that could reasonably be attributed to the measurand. The measurement uncertainty indicates how the test result represents the actual value. Evalution of measurement uncertainty contributes to the improvement of the quality of clinical laboratories and the interpretation of specific results. The measurement uncertainty is a quantitative indicator of the quality of a blood test result and is a fundamental requirement for laboratory accreditation. International Organization for Standardization recommends that laboratories calculate the measurement uncertainty for each test that they measure and have it available for reporting upon request of the clinician. In this study, we aimed to calculate the measurement uncertainties of the tests used in the evaluation of iron deficiency anemia in Ege University Faculty of Medicine Clinical Biochemistry Laboratory. Methods: The measurement uncertainty for the erythrocyte count, hemoglobin, hematocrit, MCV, MCH, MCHC, leukocyte count, platelet count, serum iron, unsaturated iron binding capacity, serum transferrin and ferritin were estimated by using the internal and external quality control data between May 2018 and April 2019 according to the Nordtest method. The measurement uncertainty results were then compared with the international accepted total allowable error limits (Westgard and CLIA'88). Results: The expanded measurement uncertainty values for the left and right modules of Sysmex XN-2000 and XN-3100 respectively were calculated as 3.84%, 2.17%, 4.58%, 1.61% for erythrocyte, 2.61%, 2.31%, 3.65%, 1.75% for hemoglobin, 4.78%, 5.89%, 6.85%, 7.02% for hematocrit, 7.47%, 6.00%, 6.14%, 7.48% for MCV, 2.95%, 1.91%, 1.92%, 1.93% for MCH, 5.80%, 9.66%, 5.27%, 5.96% for MCHC, 4.03%, 3.86%, 8.17%, 6.02% for leukocytes and 12.72%, 14.02%, 10.98%, 11.37% for platelets; 9.71% for iron, 10.51% for ansature iron binding capacity, 6.89% for transferrin and 25% for ferritin. The expanded uncertainty values of hemoglobin, leukocyte and iron were within the total allowable error limits determined by Westgard and CLIA. Conclusion: Each laboratory should calculate the uncertainty values of the tests and check these values at regular intervals for monitoring analytical performance. Calculation of measurement uncertainty of the tests used in the evaluation of iron deficiency anemia, which is one of the most common causes of anemia in our country and reporting these values together with the test results will increase the physician's ability at the point of clinical decision making and the confidence in the laboratory results and will make a significant contribution to the health care provided to the patients.