When your RDW (Red Cell Distribution Width) value in a blood test is below the reference range, it indicates that your red blood cells are more similar and uniform in size. This means there is less variation in the size of your red blood cells. Low RDW alone is generally not a clinical concern and, in most cases, does not indicate a serious health problem. Symptoms such as diarrhea, heart palpitations, fatigue, or nausea are not a direct result of low RDW; these types of complaints are usually associated with other underlying health issues. The RDW value is part of a complete blood count and should be evaluated by a physician along with other blood parameters.