From the Guidelines
The initial workup for anemia should include a complete blood count (CBC) with differential, peripheral blood smear, reticulocyte count, iron studies (serum iron, total iron binding capacity, ferritin), vitamin B12, folate levels, and a comprehensive metabolic panel, as recommended by the British Society of Gastroenterology guidelines for the management of iron deficiency anaemia in adults 1. The diagnosis of anemia is based on a hemoglobin concentration below the lower limit of normal for the relevant population and laboratory performing the test, with iron deficiency confirmed by iron studies prior to investigation, and serum ferritin being the single most useful marker of iron deficiency anemia (IDA) 1. Additional testing may include hemoglobin electrophoresis, direct Coombs test, and erythropoietin levels depending on initial findings. For iron deficiency anemia, treatment with oral ferrous sulfate or ferrous gluconate is recommended, with a good response to iron therapy (Hb rise ≥10 g/L within a 2-week timeframe) being highly suggestive of absolute iron deficiency, even if the results of iron studies are equivocal 1. In patients with inflammatory bowel disease (IBD), iron supplementation is recommended when iron-deficiency anemia is present, with intravenous iron being more effective and better tolerated than oral iron in patients with clinically active IBD, previous intolerance to oral iron, or hemoglobin below 100 g/L 1. Anemia classification based on red cell size (microcytic, normocytic, macrocytic) and reticulocyte count helps narrow the differential diagnosis, with microcytic anemias suggesting iron deficiency or thalassemia, normocytic anemias indicating chronic disease or hemolysis, and macrocytic anemias pointing to B12/folate deficiency or liver disease. The underlying cause of anemia must be identified and addressed, such as occult bleeding in iron deficiency or autoimmune conditions in hemolytic anemia, with regular monitoring of complete blood counts, CRP, and serum ferritin to detect anemia, inflammatory flare, or iron deficiency at an early stage 1. Key points to consider in the workup and management of anemia include:
- Complete blood count (CBC) with differential
- Peripheral blood smear
- Reticulocyte count
- Iron studies (serum iron, total iron binding capacity, ferritin)
- Vitamin B12 and folate levels
- Comprehensive metabolic panel
- Hemoglobin electrophoresis, direct Coombs test, and erythropoietin levels as needed
- Treatment with oral ferrous sulfate or ferrous gluconate for iron deficiency anemia
- Intravenous iron for patients with clinically active IBD, previous intolerance to oral iron, or hemoglobin below 100 g/L
- Regular monitoring of complete blood counts, CRP, and serum ferritin to detect anemia, inflammatory flare, or iron deficiency at an early stage.
From the Research
Anemia Workup
- Anemia is a common condition that requires investigation to determine the cause and provide appropriate treatment 2, 3
- Initial evaluation consists of a thorough history and physical examination, and a complete blood cell count (CBC) 2
- The CBC and mean corpuscular volume provide important clues to the classification and cause of anemia 2
- Supplemental tests may include:
- Peripheral blood smear
- Reticulocyte count
- Iron panel (ferritin and iron levels, total iron-binding capacity, transferrin saturation)
- Levels of vitamin B12, folate, lactate dehydrogenase, haptoglobin, and bilirubin 2
- Testing for specific causes of anemia is performed, and occasionally, examination of the bone marrow is required for diagnosis 3
- Molecular testing is increasingly being used to aid the diagnostic process 3
Iron Deficiency Anemia
- Iron deficiency anemia is a common condition that affects approximately 1.2 billion people worldwide, including 10 million in the US 4
- The most common causes of iron deficiency are bleeding, impaired iron absorption, inadequate dietary iron intake, and pregnancy 4
- Testing for iron deficiency is indicated for patients with anemia and/or symptoms of iron deficiency, and should be considered for those with risk factors such as heavy menstrual bleeding, pregnancy, or inflammatory bowel disease 4
- Iron deficiency is diagnosed by low serum ferritin or transferrin saturation, and causes of iron deficiency should be identified and treated 4
- Serum iron and total iron binding capacity (TIBC) are not reliable tests for diagnosing iron deficiency anemia, and ferritin is the preferred test 5