RDW: what your result means.

Variation in red blood cell size; elevated values may signal nutritional deficiency. RDW is measured by blood test as part of the Organ panel in the HodieLabs Health Blueprint.

Why RDW matters

RDW measures variation in red cell size (anisocytosis). Elevated means mixed cell populations. Elevated RDW is an independent predictor of all-cause mortality even with normal haemoglobin.

Associated risks when out of range: All-cause mortality proxy (elevated). Nutrient deficiency/inflammation (contextual).

Evidence basis

The HodieLabs Evidence-Based Clinical Library classifies RDW as an strong evidence-tier biomarker. Its reference ranges come from a published authority standard rather than from observational optimisation targets. The standard used here is Aligned with largest Australian pathology laboratory reference interval; RDW 11–17%. Previous Hodie range (11.5–14.5) was a narrowed longevity range, not the standard reference. Where relevant clinical outcomes are noted on this page, they reflect the guideline literature referenced below.

Evidence-based reference ranges

The HodieLabs Evidence-Based Clinical Library interprets RDW against published clinical authority standards, never arbitrary "optimal" ranges. Measured in %:

Clinical interpretation

• RDW measures variation in red cell size (anisocytosis). Elevated means mixed cell populations.
• Elevated RDW is an independent predictor of all-cause mortality even with normal haemoglobin.
• Classic pattern: high RDW + low MCV = iron deficiency; normal RDW + low MCV = thalassaemia trait.

What improves it: the evidence-based levers

• Elevated RDW with low MCV strongly suggests iron deficiency (vs thalassaemia which has normal RDW)
• RDW is a powerful discriminator between iron deficiency anaemia and thalassaemia trait

Recommended testing frequency: Annual, as part of a comprehensive panel. Single markers are always interpreted in context.

How RDW testing works at HodieLabs

RDW is measured in every Health Blueprint at our Melbourne Preventative Health & Longevity Clinic, interpreted by a doctor against the guideline-cited ranges above and tracked over time through your HodieLabs membership.

References

1. Aligned with largest Australian pathology laboratory reference interval; RDW 11–17%. Previous Hodie range (11.5–14.5) was a narrowed longevity range, not the standard reference.

This page is general information from the HodieLabs Evidence-Based Clinical Library, not medical advice. Speak with your GP about what testing and care is appropriate for you.