RDW-SD

RDW-SD (Red Cell Distribution Width - Standard Deviation) measures the absolute variation in red blood cell size (width of the RBC volume distribution curve at 20% height).

Category: Complete Blood Count

Also known as: rdw-sd

Reference range: 36.6–50.8 fl (Source: ABIM)

Standard unit: fl

High values may indicate

Elevated RDW-SD may indicate anisocytosis (variation in RBC size), seen in iron deficiency anemia, vitamin B12/folate deficiency, or mixed anemias.

Low values may indicate

Low values are generally not clinically significant.

Source: BloodId admin-reviewed

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