From the Guidelines
A low-normal RDW typically indicates good health with consistent red blood cell production, suggesting adequate iron, vitamin B12, and folate levels, and is associated with reduced risk of anemia and certain cardiovascular conditions. RDW measures the variation in red blood cell size, with a normal range usually between 11.5-14.5% 1. Being at the lower end of this range suggests your bone marrow is producing uniformly sized red blood cells, which is generally a positive sign. This uniformity often correlates with adequate nutrient levels, as deficiencies in these nutrients can cause variation in cell size, such as iron-deficiency anemia, which usually causes greater variation in red blood cell size than does thalassemia minor 1. Some key points to consider include:
- Low-normal RDW values are associated with reduced risk of anemia and certain cardiovascular conditions
- RDW should always be interpreted alongside other blood test results like hemoglobin and hematocrit
- If you're concerned about consistently low-normal readings, discuss them with your healthcare provider during your next visit, especially if you have other health concerns or symptoms
- A low MCV and an RDW of less than or equal to 14.0% may indicate thalassemia minor, whereas a low MCV and an RDW of greater than 14.0% indicates iron-deficiency anemia 1 No specific action is needed if your other blood parameters are normal and you have no symptoms.
From the Research
RDW Levels and Their Implications
- A low RDW (Red Cell Distribution Width) level, typically on the lowest end of normal, may indicate a few possible conditions, although there is limited direct research on this specific topic.
- RDW is a measure of the variation in red blood cell size, and a low RDW suggests that the red blood cells are relatively uniform in size.
Iron Deficiency and RDW
- Studies have shown that iron deficiency anemia (IDA) can affect RDW levels, but the provided studies do not directly address the implications of a low RDW level 2, 3.
- Iron deficiency anemia is a common condition that can be caused by various factors, including gastrointestinal bleeding, menstruation, and decreased dietary iron intake 3.
- Treatment of IDA typically involves replenishing iron stores and returning hemoglobin to a normal level, which can improve quality of life and outcomes in various conditions 3.
Other Factors Influencing RDW
- Other factors, such as the type of iron supplement used, can influence iron absorption and RDW levels 4, 5.
- For example, a study comparing slow-release and rapidly-disintegrating ferrous sulfate tablets found that the slow-release tablets resulted in higher iron absorption in all groups of subjects, including normal subjects, blood donors, and patients with iron deficiency anemia 4.
- Another study found that lactoferrin supplementation had better effects on serum iron, ferritin, and hemoglobin concentration compared to ferrous sulfate supplementation, but had a reducing effect on fractional iron absorption 5.
Limited Relevance of Provided Studies
- The provided studies do not directly address the implications of a low RDW level, and more research is needed to fully understand the significance of this finding.
- However, the studies do provide insight into the factors that can influence iron deficiency anemia and RDW levels, such as iron supplementation and absorption 2, 3, 4, 5.