RDW is a measure of the heterogeneity of the RBC population.It is derived from the RBC histogram using the 20th and 80th percentiles.
EDTA draw tube at least half full
2 mL screw-cap tube
2-8 C (ice packs) or frozen
store at 2-8 C up to 3 days, frozen at -20C to -80C for up to 6 weeks
Major Risk for heart disease-<40 mg/dL Negative risk for heart disease->60 mg/dL