neoplastic, inflammatory, infectious, foreign body) and extra-GI tract disorders ( e.g. rice, tofu, fish) for several days before testing.12-14 If the GI tract appears to be the most likely source of blood loss, both primary GI disease ( e.g. However, diets with high hemoglobin content are associated with false positive results, and patients should be fed white foods ( e.g. Ultrasonography with or without cystoscopy may be needed to identify the cause.įecal occult blood tests can confirm blood loss at volumes 2% to 5% of those associated with melena. Blood loss from the urinary system can be intermittent but is strongly suggested by gross hematuria. This peptide hormone is produced by the liver and plays a key role in iron homeostasis, uptake, and distribution.7 It is thought that inflammatory cytokines promote production of hepcidin.Ĭoncurrent determination of total iron-binding capacity along with serum iron concentrations is necessary to confirm IDA.2 If iron is truly scarce, total iron-binding capacity usually increases and percent saturation falls to 25.11 Bear in mind that blood that is coughed and swallowed from the respiratory tract will also increase this value. This process appears to be triggered, at least in part, by increased hepcidin concentrations. In many patients with chronic inflammatory, infectious, or neoplastic conditions, iron is sequestered in the bone marrow and reticuloendothelial organs, and serum concentrations may fall below the reference range despite adequate iron stores. However, low serum iron concentrations have poor specificity for IDA. Samples must be collected carefully to avoid ex vivo hemolysis, which may affect accuracy. Serum iron concentrations can be inexpensively determined by using ferrozine-based methods. Thrombocytopenia has been occasionally reported in dogs with IDA. The cause of this thrombocytosis is unknown.
Many IDA patients have increased platelet numbers. Iron deficiency should not be discounted just because the absolute reticulocyte count is > 60,000/μl.2 In fact, reticulocyte production is variable and may be fairly robust. It is a common misconception that IDA is a nonregenerative process. It appears to reflect abnormal iron metabolism but is not associated with true iron deficiency. The other well-recognized cause of microcytosis, with or without anemia, is portosystemic shunting.3-6 The reason for this is unclear. That is normal for these dogs and does not need to be investigated. Small RBCs, without anemia, are sometimes noted in Akitas and other Japanese dog breeds. Microcytosis is an otherwise uncommon finding, and IDA should be considered in every patient with microcytic anemia. The hallmark of IDA is microcytic hypochromic anemia, which is indicated by a low mean corpuscular volume and a low mean corpuscular hemoglobin or hemoglobin concentration.1,2 The RBC distribution width is often increased and simply reflects substantial variation in erythrocyte sizes it may be reported by a technologist as anisocytosis. This behavior often resolves when iron stores are replenished. Both dogs and cats may eat soil or rocks indoor cats may ingest litter. Unusual food cravings, or pica, may be reported. Patients may have a high resting heart rate and tachypnea, with a low-grade systolic heart murmur. On physical examination, mucous membranes will be variably pale. The onset may be insidious, with progressive lethargy, fatigue, and exercise intolerance. The clinical signs of IDA are related to decreased red blood cell (RBC) mass and oxygen-carrying capacity.
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