American Association for Clinical Chemistry
Better health through laboratory medicine
NACB - Scientific Shorts
NACB - Scientific Shorts (formerly NACB Blog)
By William Winter, MD

A middle-aged woman was under the care of her physician for anemia. The following laboratory results were obtained at a time when the patient was not acutely ill.

                            Patient results       Reference intervals
Serum iron             1400 ug/dL            42 -135 ug/dL
TIBC                      1250 ug/dL          225 - 430 ug/dL
% Tf saturation          112%                 20-55%

 (Tf = transferrin)

I was contacted by our laboratory supervisor to review these results because of these extreme elevations. What is the cause of these extreme elevations?


Prior to having the patient's blood drawn, the physician had injected the patient with IM iron (e.g, ImferonR). ImferonR produces marked elevations in the serum iron and TIBC. Iron, TIBC and % Tf saturation can not be interpreted until the iron-dextran complexes (or other iron-complexes) have been cleared. Other brand names for iron-dextran include InFeD, Dexiron (in Canada) and Infufer (in Canada). The half-life of iron-dextran complexes is 5 to 20 hours.

As a side note, before any adult patient with iron deficiency is treated with iron, the possibility of iron loss must be considered. This can require lower GI tract endoscopy. If the colon is free of lesions, upper endoscopy should next be pursued so as to not miss cases of esophageal disease. While fecal occult blood testing (FOBT) should be obtained, endoscopy is still required even if the FOBT is negative. If there is no evidence for blood loss, then iron malabsorption must be considered.







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About the Author
William Winter, MD
William Winter, MD