What is the clinical significance of normal CBC results with slightly elevated RDW in an adult patient?

CBC Interpretation: Normal Results with Borderline RDW

These CBC results are entirely normal and require no intervention. The RDW of 13.0% falls within the normal reference range (11.5-14.5%) and does not indicate any pathology requiring clinical action 1.

Complete Blood Count Analysis

White Blood Cell Parameters - Normal

• WBC 7.0 × 10³/μL: Within normal adult range (3.5-10.0 × 10³/μL) 2
• Neutrophil percentage 71.6%: Normal range, not elevated (>90% would suggest bacterial infection) 3
• Absolute neutrophil count 5.0 × 10³/μL: Normal, no neutrophilia present 3
• No left shift: Band forms would need to be ≥16% or absolute band count ≥1,500/mm³ to indicate bacterial infection, which is not present here 4
• Lymphocyte, monocyte, eosinophil, and basophil counts: All within normal limits 2

Red Blood Cell Parameters - Normal

• Hemoglobin 14.8 g/dL: Normal for adults (no anemia present) 5
• Hematocrit 43.9%: Normal 5
• MCV 89.8 fL: Normocytic (normal size red blood cells) 1
• MCH and MCHC: Both normal, indicating appropriate hemoglobin concentration 1
• RBC count 4.9 × 10⁶/μL: Normal 1

RDW 13.0% - Normal, Not Clinically Significant

• This value is within the normal reference range (typically 11.5-14.5%) and does not represent pathology 1
• RDW becomes clinically significant only when >14.0%, at which point it may indicate increased variation in red blood cell size and decreased deformability 6
• The threshold of 14.0% has been associated with cardiovascular risk in research studies, but this patient's value of 13.0% is below this threshold 6
• RDW elevation (when present) can indicate iron deficiency anemia, vitamin B12/folate deficiency, hemolysis, or bone marrow dysfunction—none of which are suggested by this normal CBC 7, 1

Platelet Parameters - Normal

• Platelet count 219 × 10³/μL: Normal (150-400 × 10³/μL) 5
• MPV 9.2 fL: Normal mean platelet volume 1

Clinical Significance

No pathology is present in this CBC. All parameters fall within normal reference ranges, including the RDW 1. The patient shows:

• No evidence of infection (normal WBC, no left shift, normal neutrophil percentage) 4, 3
• No anemia (normal hemoglobin, hematocrit, RBC indices) 1
• No thrombocytopenia or thrombocytosis 5
• No increased red blood cell size variation that would suggest underlying disease 6

Common Pitfalls to Avoid

• Do not overinterpret borderline-normal values: An RDW of 13.0% is normal and does not require investigation or follow-up 1, 6
• Do not order additional testing based on this normal CBC: No hematologic abnormalities are present that would warrant further workup 1
• Do not assume RDW has clinical significance at normal values: The prognostic associations with cardiovascular disease apply only when RDW exceeds 14.0% 6