Biomarkers · Hematology

Red Cell Distribution Width (RDW)

Lower values go with lower risk of death. In NHANES 1999–2018 with linked mortality to 2019, each standard deviation above average goes with 40% higher risk of death. We found the same pattern in NHANES

RDW and risk of death

NHANES, our fit with 95% CIPublished curve

Published curve higher than the NHANES fitNHANES fit higher

Risk of death relative to each curve's own reference value, so the two curves need not cross 1 at the same point. The dotted vertical line marks the NHANES median.

Risk of death per SD (NHANES)1.40×95% CI 1.37–1.43 · 49,105 adults, 7,188 deaths

Published risk of death1.23×per 1-SD increment in RDW (0.98%) (95% CI 1.18–1.28) · NHANES III (1988-1994) adults, nationally representative US sample, mortality follow-up through December 31, 2000

Value of the measurement+0.038gain in concordance within age bands; rank 5 of 56 · all tests

RDW by age and sex

Each bar runs from the 5th to the 95th percentile, the darker part from the 25th to the 75th, and the tick is the median. Not a reference range or a target.

The percentiles as a table

Each row is one sex and age band: the values below which 5%, 25%, 50%, 75% and 95% of people fall (%), from the survey named in the row. Not a reference range or a target.
Sex	Age	5th	25th	Median	75th	95th	n	Cycle / source
All	20-39	12.4	12.8	13.2	13.8	15.6	1,457	NHANES 2017-2018
All	40-59	12.4	13.0	13.4	14.0	16.2	1,584	NHANES 2017-2018
All	60+	12.6	13.2	13.7	14.4	16.0	1,940	NHANES 2017-2018
All	all	12.5	13.0	13.4	14.0	15.9	4,981	NHANES 2017-2018
Men	20-39	12.4	12.8	13.1	13.6	14.7	698	NHANES 2017-2018
Men	40-59	12.4	13.0	13.4	13.9	14.9	740	NHANES 2017-2018
Men	60+	12.7	13.2	13.7	14.4	15.9	981	NHANES 2017-2018
Men	all	12.5	13.0	13.4	13.9	15.3	2,419	NHANES 2017-2018
Women	20-39	12.3	12.8	13.3	14.1	16.2	759	NHANES 2017-2018
Women	40-59	12.4	13.0	13.4	14.1	16.9	844	NHANES 2017-2018
Women	60+	12.6	13.2	13.7	14.3	16.2	959	NHANES 2017-2018
Women	all	12.4	13.0	13.5	14.2	16.6	2,562	NHANES 2017-2018

What studies found when this marker was changed

They describe what happened in those study groups, not a recommendation. See all catalogued interventions.

Measured changes in RDW, study by study

1 effect with a numeric size, each from one study arm: the dot is the reported change, the line its 95% interval where one was given. Green points move the marker the way lower risk of death lies; amber the other way. Study results in the groups studied, not predictions for a person.

Each row is one study: what was changed, the effect it reported on this marker, and the source.
Type	Intervention	Reported effect	Evidence	Source
nutraceutical	Correction of iron deficiency (IV ferric carboxymaltose)	IV iron lowered RDW below placebo at 24 weeks (-1.0%, P = 0.03) after a transient +0.54% rise at 4 weeks	RCT	Van Craenenbroeck EM, et al. The effect of intravenous ferric carboxymaltose on…
supplement	Iron repletion maintenance (low-dose iron during menstruation after iron deficiency anaemia)	After IDA treatment, maintenance iron kept RDW stable while RDW rose markedly in untreated controls; anaemia recurrence 8.1% vs 32.3% at 12 months	cohort	Irmak Kaya Z, et al. Low-dose iron therapy during menstruation to prevent…

Things that worsen it

Each row is one study: what was changed, the effect it reported on this marker, and the source.
Type	Condition or exposure	Reported effect	Evidence	Source
clinical	Heart failure (vs healthy controls)	RDW 14.28 in heart failure patients vs 13.47 in healthy controls (p < 0.001)	cross-sectional	Torfi E, et al. Evaluation of Pro-BNP biomarker in heart failure patients and…
clinical	Chronic kidney disease (reduced eGFR)	Lower eGFR independently predicted higher RDW; eGFR<60 prevalence rose from 5 % to 19 % across RDW quartiles (n=8,585)	cross-sectional	Lippi G, et al. Relationship between red blood cell distribution width and…
environmental	Chronic systemic inflammatory state and oxidative erythrocyte membrane fragility	Increased RDW reflects deregulated erythropoiesis and red cell survival linked to oxidative stress, inflammation and poor nutrition (effect size not reported)	review	Salvagno GL, et al. Red blood cell distribution width: A simple parameter with…

What else moves this marker

They describe those study groups, not an individual, and an association is not a cause.

Diseases and conditions

Each row is one study: what it compared and the change it reported in this marker.
What	Effect on the marker	Comparison · population	Source
↑ Ankylosing spondylitis · AS patients vs healthy controls	SMD +0.67 (95% CI 0.3 to 1.05)	AS vs healthy controls · 775 AS patients and 972 healthy controls, 9 studies	meta analysis · PMID 31478944
↑ Psoriasis · psoriasis patients vs healthy volunteers	SMD +0.522 (95% CI 0.228 to 0.817)	psoriasis vs healthy controls · 1331 psoriasis patients and 919 healthy volunteers (RDW in 4 studies)	meta analysis · PMID 35213665

Sources

Risk curve: Perlstein TS 2009 (PMID 19307522): all-cause HR 1.23 (1.18-1.28) per 1-SD increment in RDW (0.98%). Scaled to US values (NHANES).
Perlstein TS, Weuve J, Pfeffer MA, Beckman JA. Red blood cell distribution width and mortality risk in a community-based prospective cohort. Arch Intern Med. 2009;169(6):588-94.
Patel KV, Semba RD, Ferrucci L, Newman AB, Fried LP, Wallace RB, et al. Red cell distribution width and mortality in older adults: a meta-analysis. J Gerontol A Biol Sci Med Sci. 2010;65(3):258-65.
NHANES curve: our Cox model adjusted for age and sex, NHANES 1999–2018 with linked mortality to 2019.

Map Red Cell Distribution Width (RDW) against another biomarker · Featured: Red cell width (RDW) × albumin.

Map RDW against another marker