RDW (Red Cell Distribution Width)

Routine annual

also —

What it isThe coefficient of variation of red blood cell sizes — how uniformly sized the red cells are in a sample. Low RDW means uniform cells; high RDW means a mix of sizes.

DoesCaptures the diversity of red cell ages and sources, which reflects the smoothness of marrow production.

GoodA low RDW signals consistent erythropoiesis and tracks lower all-cause mortality.

BadElevated RDW is one of the strongest single markers of all-cause mortality, even within the "normal" range. It rises before anemia in iron, B12, or folate deficiency.

Standard

11.5–14.5%.

Optimal

11.5–12.5% (lower is good)

Modifiers

Rises with mixed deficiencies (iron + B12), chronic disease, inflammation.

How to optimize

Lifestyle: Address sleep, stress, inflammation drivers; resistance training; treat sleep apnea.
Diet: Whole-food nutrient density; address iron, B12, folate gaps.
Supplements: Methylcobalamin (1000µg/day), methylfolate (400–800µg/day), iron (if deficient), pyridoxal-5-phosphate (B6, 25mg/day).
Peptides: —
Drugs: Treat underlying cause.

within Blood Cells