Iron Deficiency Anemia Diagnosis and Treatment

Diagnostic Criteria

The combination of low MCHC, low transferrin saturation, and high TIBC is diagnostic of iron deficiency anemia, and treatment should begin with oral iron supplementation unless specific contraindications exist, as recommended by the American Gastroenterological Association 1, 2
Low MCHC indicates hypochromic red cells, a hallmark of iron-deficient erythropoiesis, with a strength of evidence level of high 1, 2
High TIBC reflects increased transferrin production by the liver attempting to capture any available iron, with a strength of evidence level of moderate 2, 3
Transferrin saturation (TSAT) is calculated as (serum iron / TIBC) × 100, and values <16-20% confirm iron deficiency, with a specificity of 0.99 for serum ferritin <15 μg/L 3

Serum ferritin is the most specific test for iron deficiency, with <15 μg/L being highly specific, <30 μg/L indicating depleted iron stores, and <45 μg/L warranting investigation even with inflammation, as recommended by the American College of Gastroenterology 1, 2
Complete blood count with MCV and RDW is necessary to assess microcytosis, with a strength of evidence level of high 2, 4
Reticulocyte count is necessary to evaluate bone marrow response, with a strength of evidence level of moderate 4
CRP is necessary to identify inflammation that might elevate ferritin falsely, with a strength of evidence level of high 1, 2, 4

Oral iron is the initial treatment for most patients with IDA, with expected response of 1-2 g/dL hemoglobin increase within one month, as recommended by the American Gastroenterological Association 1, 2
IV iron is preferred when oral iron intolerance or non-adherence, malabsorption, heavy ongoing blood loss, or rapid iron repletion is needed, with a strength of evidence level of moderate 3
Monitoring of treatment response includes hemoglobin, hematocrit, serum ferritin, transferrin saturation, and reticulocyte hemoglobin content, with a strength of evidence level of high 3