Diagnostic Approach and Management of Anemia

Initial Diagnostic Evaluation

The American College of Physicians recommends that anemia is defined as hemoglobin < 13 g/dL in men and < 12 g/dL in non-pregnant women (< 11 g/dL in pregnant women) 1
Classification by mean corpuscular volume (MCV) guides the differential diagnosis, with microcytic anemia (MCV < 80 fL) suggesting iron deficiency, thalassemia, or anemia of chronic inflammation, as recommended by the American Society of Hematology 2, 1
Normocytic anemia (MCV 80-100 fL) may indicate acute blood loss, hemolysis, anemia of chronic disease, or early iron deficiency, according to the American College of Physicians 2, 1
Macrocytic anemia (MCV > 100 fL) may be caused by vitamin B12/folate deficiency, medications, alcohol use, or myelodysplastic syndrome, as stated by the American Society of Hematology 1, 3

A complete blood count with red cell indices is a crucial initial test, as recommended by the American College of Physicians 2, 1
Reticulocyte count helps distinguish between impaired production and increased destruction or blood loss, according to the American Society of Hematology 1
Iron studies, including serum ferritin, transferrin saturation, and total iron-binding capacity, are essential for diagnosing iron deficiency anemia, as stated by the National Institute of Diabetes and Digestive and Kidney Diseases 4, 1
Inflammatory markers, such as C-reactive protein (CRP), can help identify anemia of chronic disease, as recommended by the American College of Physicians 2, 1

The American College of Physicians recommends diagnostic criteria for iron deficiency anemia, including serum ferritin < 30 μg/L without inflammation 1
Treatment options for iron deficiency anemia include oral iron supplementation, as recommended by the American Gastroenterological Association 1

The American College of Physicians recommends that primary treatment involves addressing the underlying condition 1

Regular monitoring of hemoglobin levels is crucial, with checks at least every three months in patients with GFR < 30 ml/min, as recommended by the National Kidney Foundation 5
A complete workup is necessary if hemoglobin levels are < 12 g/dL in women or < 13 g/dL in men, according to the National Kidney Foundation 5
Treatment approach includes treating iron deficiency and considering erythropoietin therapy if anemia persists despite iron therapy, as stated by the National Kidney Foundation 5

Genetic disorders causing microcytic anemia require specialized testing and management, as recommended by the American Society of Hematology 4, 6
The American Geriatrics Society recommends that elderly patients with anemia should not be considered as having a normal physiological response to aging, and a comprehensive evaluation is necessary 1
Patients with inflammatory bowel disease often have multifactorial anemia, requiring a comprehensive evaluation, as stated by the American Gastroenterological Association 1

The American College of Physicians recommends investigating the cause of anemia, especially in elderly patients, to avoid missing concurrent nutritional deficiencies, such as combined iron and B12 deficiency 1

The European Society of Medical Oncology recommends that when ferritin is elevated (> 100 μg/L) with low TSAT (< 20%), anemia of chronic disease/inflammation should be considered and C-reactive protein (CRP) should be measured 7, 8
The American Society of Hematology suggests that if ferritin is elevated AND TSAT is elevated or when TSAT is low with ferritin 20-100 μg/L, genetic disorders of iron metabolism or heme synthesis (sideroblastic anemia, IRIDA, hemochromatosis) should be suspected 9, 10
Hemoglobin electrophoresis should be ordered if iron studies are normal to evaluate for thalassemia, as recommended by the National Heart, Lung, and Blood Institute 10

The National Kidney Foundation recommends that in patients with chronic kidney disease, hemoglobin should be monitored every 3 months when GFR < 30 mL/min, and a complete workup is required if hemoglobin < 12 g/dL in women or < 13 g/dL in men 7, 8
The Crohn's and Colitis Foundation of America suggests that in patients with inflammatory bowel disease, anemia is typically multifactorial (iron deficiency from blood loss plus anemia of chronic disease) and minimum screening should include CBC, CRP, and serum ferritin at regular intervals based on disease activity 7, 8

The American Society of Human Genetics recommends considering genetic disorders when microcytic anemia is refractory to iron supplementation, there is a family history of anemia, or ferritin > 100 μg/L with elevated TSAT (suggests iron loading disorders) 9, 10
For X-linked sideroblastic anemia (XLSA), the National Institutes of Health recommends screening male probands' mothers, sisters, and daughters—female carriers can develop phenotype later in life 9

In inflammatory states, ferritin up to 100 μg/L may still indicate iron deficiency; measure C-reactive protein (CRP) to assess inflammation, as recommended by the Journal of Crohn's and Colitis 11
The European Society of Gastrointestinal Endoscopy suggests that all adults with confirmed iron deficiency anemia require urinalysis/urine microscopy, celiac disease screening, and in appropriate cases, upper and lower GI endoscopy 12

In patients with inflammatory bowel disease, anemia is typically multifactorial, including iron deficiency from blood loss plus anemia of chronic disease, and disease-specific ferritin thresholds should be used, such as <30 μg/L without inflammation, up to 100 μg/L with inflammation, as recommended by the Journal of Crohn's and Colitis 11
The National Institute for Health and Care Excellence recommends that patients with chronic kidney disease should have their hemoglobin levels monitored every 3 months when GFR <30 mL/min, and a complete workup is required if hemoglobin <12 g/dL in women or <13 g/dL in men 12

The American Gastroenterological Association suggests that diagnostic criteria for anemia of chronic disease/inflammation include serum ferritin >100 μg/L and TSAT <20% in the presence of inflammation, as recommended by the Journal of Crohn's and Colitis 11
If ferritin is between 30-100 μg/L, a combination of true iron deficiency and anemia of chronic disease is likely, as recommended by the Journal of Crohn's and Colitis 11