RDW (Red Cell Distribution Width)
Routine annualalso —
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.
Reference ranges are general adult lab norms; optimal ranges are editorial picks from the longevity literature — not medical advice. Always interpret results with your physician.
within Blood Cells