From the Guidelines
RDW is a crucial parameter in diagnosing and managing anemia, as it helps distinguish between different types of anemia and other conditions, with elevated values indicating iron deficiency anemia, vitamin B12 or folate deficiency, and hemolytic anemia. The significance of RDW lies in its ability to provide diagnostic clues when interpreted alongside other blood parameters like hemoglobin, MCV (Mean Corpuscular Volume), and MCH (Mean Corpuscular Hemoglobin) 1. A high RDW value can indicate a wide range of red cell sizes, which can be seen in iron deficiency anemia, and can help diagnose this condition even when the MCV is normal 1.
Some key points to consider when interpreting RDW values include:
- Elevated RDW values are associated with iron deficiency anemia, vitamin B12 or folate deficiency, and hemolytic anemia 1
- Normal RDW with low hemoglobin might suggest chronic disease anemia or thalassemia 1
- RDW can be used to distinguish between iron deficiency anemia and anemia of chronic disease (ACD) in patients with inflammatory bowel disease (IBD) 1
- A comprehensive workup for anemia should include complete blood count with MCV, reticulocytes, serum ferritin, transferrin saturation, and CRP, as well as vitamin B12 and folic acid levels if necessary 1
It's worth noting that while older studies may provide some insight into the management of iron deficiency anemia, such as the 2000 guidelines from the British Society of Gastroenterology 1, the most recent and highest quality evidence should be prioritized when making clinical decisions. Therefore, the 2015 European Consensus on the diagnosis and management of iron deficiency and anaemia in inflammatory bowel diseases 1 should be considered the most relevant and up-to-date guidance on this topic.
From the Research
Significance of RDW
The red blood cell distribution width (RDW) is a parameter that reflects the degree of heterogeneity of erythrocyte volume, and its significance extends beyond its traditional use in laboratory hematology for differential diagnosis of anemias 2. Some key points about the significance of RDW include:
- RDW is a simple and inexpensive parameter that can provide important information for short- and long-term prognosis 2
- An increased RDW has a high negative predictive value for diagnosing a variety of disorders, including cardiovascular disease, venous thromboembolism, cancer, diabetes, and chronic obstructive pulmonary disease 2
- RDW is now being regarded as a strong and independent risk factor for death in the general population 2
- RDW mirrors a profound deregulation of erythrocyte homeostasis involving both impaired erythropoiesis and abnormal red blood cell survival, which may be attributed to underlying metabolic abnormalities such as oxidative stress, inflammation, and poor nutritional status 2
Clinical Applications of RDW
The clinical applications of RDW are diverse and include:
- Diagnostic and prognostic information in patients with cardiovascular and thrombotic disorders 3
- Prediction of iron and folate deficiency anemias from standard blood testing 4
- Detection of folate deficiency and limitation of fetal damage in individuals and communities 4
- Evaluation of anemia, including classification by mean corpuscular volume and diagnosis of iron deficiency anemia, normocytic anemia, and macrocytic anemias 5
- Association with adverse outcomes in patients with acute coronary syndrome, ischemic cerebrovascular disease, peripheral artery disease, heart failure, and atrial fibrillation 6
RDW and Cardiovascular Diseases
The relationship between RDW and cardiovascular diseases is significant, with:
- Emerging evidence suggesting that an increased RDW value is associated with acute coronary syndrome, ischemic cerebrovascular disease, peripheral artery disease, atrial fibrillation, heart failure, and hypertension 6
- Higher anisocytosis significantly and independently predicting adverse outcomes in patients with these conditions 6
- The clinical use of RDW being broadened beyond the conventional boundaries of erythrocyte disorders, in particular for assisting the diagnosis and prognostication of patients with cardiovascular diseases 6