Initial Workup and Treatment for Anemia
The initial workup for anemia should include a complete blood count with red cell indices, reticulocyte count, iron studies (serum ferritin, transferrin saturation, total iron-binding capacity), and inflammatory markers, followed by targeted treatment based on the underlying cause. 1, 2
Diagnostic Approach
Definition and Classification
- Anemia is defined as hemoglobin < 13 g/dL in men and < 12 g/dL in non-pregnant women (< 11 g/dL in pregnant women) 2
- Classification by mean corpuscular volume (MCV) guides the differential diagnosis: 3, 1
- Microcytic (MCV < 80 fL): most commonly iron deficiency, thalassemia, anemia of chronic disease, sideroblastic anemia
- Normocytic (MCV 80-100 fL): hemorrhage, hemolysis, bone marrow failure, anemia of chronic inflammation, renal insufficiency
- Macrocytic (MCV > 100 fL): vitamin B12/folate deficiency, medications, alcohol use, myelodysplastic syndrome
Essential Initial Laboratory Tests
- Complete blood count (CBC) with red cell indices 1, 4
- Reticulocyte count to distinguish between production problems and blood loss/destruction 3, 2
- Iron studies: serum ferritin, iron levels, total iron-binding capacity (TIBC), transferrin saturation 1, 4
- Vitamin B12 and folate levels 3, 1
- Inflammatory markers (e.g., C-reactive protein) to identify anemia of chronic disease 2
Additional Tests Based on Initial Findings
- For suspected hemolysis: LDH, haptoglobin, bilirubin, Coombs test 3, 1
- For suspected blood loss: stool guaiac test, endoscopy 3, 5
- For suspected kidney disease: glomerular filtration rate, erythropoietin level 3
- For suspected inherited anemia: personal and family history, specialized testing 3, 2
Treatment Approach by Etiology
Iron Deficiency Anemia
- Confirmed by transferrin saturation < 15% and ferritin < 30 ng/mL 3, 6
- Identify and treat underlying cause (especially GI bleeding in men and postmenopausal women) 6, 5
- Treatment: oral iron supplementation (100-200 mg elemental iron daily) for 3-6 months 6, 5
- Consider intravenous iron for patients who cannot tolerate oral preparations, have malabsorption, or have ongoing inflammation 6, 5
Vitamin B12 Deficiency
- Treatment for pernicious anemia: intramuscular cyanocobalamin 100 mcg daily for 6-7 days, then alternate days for 7 doses, then every 3-4 days for 2-3 weeks, followed by 100 mcg monthly for life 7
- Oral supplementation may be used for patients with normal intestinal absorption 7
Anemia of Chronic Disease/Inflammation
- Primary treatment involves addressing the underlying condition 2, 8
- Consider iron supplementation, especially if concurrent iron deficiency exists 8
Anemia in Chronic Kidney Disease
- For patients with GFR < 30 ml/min/1.73 m², check hemoglobin at least every three months 3
- Complete workup if hemoglobin < 12 g/dL in women or < 13 g/dL in men 3
- Treat iron deficiency if identified 3
- Consider erythropoietin therapy if anemia persists despite appropriate evaluation and iron therapy 3
Common Pitfalls to Avoid
- Failing to investigate the cause of anemia, especially in elderly patients 2
- Missing concurrent nutritional deficiencies (e.g., combined iron and B12 deficiency) 2, 8
- Overlooking gastrointestinal malignancy in men and postmenopausal women with iron deficiency anemia 6, 5
- Treating with high-dose folic acid without ruling out B12 deficiency (may mask B12 deficiency symptoms) 1
- Relying solely on hemoglobin levels for transfusion decisions rather than considering clinical symptoms 1
Special Considerations
- Patients with chronic kidney disease require regular monitoring of hemoglobin and specific treatment protocols 3
- Elderly patients with anemia should not be considered as having a normal physiological response to aging 2
- Patients with inflammatory bowel disease often have multifactorial anemia requiring comprehensive evaluation 2
- Genetic disorders causing anemia may require specialized testing and management 2