| General Overview of Testing Tests for evaluating iron metabolism are generally used as initial or screening tests for hereditary hemochromatosis (HH) as they will detect the phenotypic expression of HH. These tests include serum iron (SI), transferrin (Tf) or total iron binding capacity (TIBC), serum ferritin (SF), and unsaturated iron binding capacity (UIBC).The serum ferritin assay is also used to assess the effectiveness of HH treatment.Molecular (DNA) analyses for HFE mutations are considered to be confirmatory tests for HH which may be ordered reflexively in patients with elevated iron results. Laboratories should establish their own reference intervals for assays of iron metabolism. In general, reference intervals vary by sex and by method used for the assays discussed in the following section. Typical reference intervals are included in the following sections for instructive purposes only and should not be used for evaluating actual patient data.The results of laboratory tests assessing iron metabolism should be interpreted with caution because a number of pre-analytical and physiologic factors can affect the results. Repeating elevated test results on fasting specimens is often advisable. | View Page |
| References 1. Beutler E. Iron storage disease: Facts, fiction and progress. Blood Cells Mol Dis. 2007;39:140-7.2. Higgins T, Beutler E, Doumas BT. Hemoglobin, iron, and bilirubin. In: Burtis CA, editor. Teitz Fundamentals of Clinical Chemistry. 6th ed. Saunders Elsevier, 2008.3. Ganz T. Hepcidin, a key regulator of iron metabolism and mediator of anemia and inflammation. Blood 2003;102(3):78-8.4. Andrews NC, Schmidt PJ. Iron homeostasis. Annu Rev Physiolo. 2007;69:69-85.5. Murtagh LJ, Whiley M, Wilson S, et al. Unsaturated iron binding capacity and transferrin saturation are equally reliable in detection of HFE hemochromatosis. Am J Gastroenterol. 2002;97(8):2093-9.6. Haddy TB, Castro OL, Rana SR. Hereditary hemochromatosis in children, adolescents, and young adults. Am J Pediatr Hematol Oncol 1988;10:23-4.7. Edwards CQ, Ajoika RS, Kushner JP. Hemochromatosis: A genetic definition. In Barton JC, Edwards CQ, eds. Hemochromatosis: Genetics, Pathophysiology, Diagnosis and Treatment. Cambridge, UK:Cambridge Univ Pr 2000:8-11.8. Whitlock EP, Garlitz BA, Harris EL , et al. Screening for Hereditary Hemochromatosis: A Systematic Review for the U.S. Preventive Services Task Force. Ann Intern Med. 2006; 145: 209-23.9. Wallace DF, Subramaniam VN. Non-HFE haemaochromatosis. World J Gastroenterol. 2007;13(35):4690-8.10. Tavill AS. Diagnosis and management of hemochromatosis. Hepatology. 2001;33:1321-811. Qaseem A, Aronson M, Fitterman N, Snow V, Weiss KB, Owens DK, et al. Screening for hereditary hemochromatosis: a clinical practice guideline from the American College of Physicians. Ann Intern Med. 2005;143:517-21.12. Phatak PD, Bonkovsky HL, and Kowdley KV. Hereditary Hemochromatosis: time for targeted screening. Ann Intern Med. 2008; 149(4): 270 – 2.13. Brissot P, deBels F. Current approaches to the management of hemochromatosis. Hematology Am Soc Hematol Educ Program. 2006:36-41. 14. Guidance for industry: Variances for blood collection from individuals with hereditary hemochromatosis. http://www.fda.gov/cber/gdlns/hemchrom.htm Accessed 12/17/08. | View Page |
| UIBC Unsaturated iron binding capacity (UIBC) may also be used as a marker for altered iron metabolism. UIBC represents the portion of iron binding sites on transferrin that are not occupied by iron. Therefore, a low UIBC indicates that transferrin is highly saturated with iron, a finding consistent with hereditary hemochromatosis (HH). HH may be suspected when the UIBC is less than 143 micrograms/dL, a criterion suggested by the results of one study.(5)UIBC may be a lower cost alternative to the more complex transferrin saturation (TS). UIBC and SI are both fully automated procedures that are available on widely used laboratory instruments. The TIBC can be calculated by adding UIBC and SI, resulting in a value for TIBC that can be used for determining TS: TS = SI/(SI + UIBC) X 100 | View Page |