Red cell distribution width correlates with fatigue levels in a diverse group of patients with [lupus] irrespective of anaemia status, 2019, Wincup et

[Andy]

OBJECTIVES:
Fatigue remains a debilitating feature of systemic lupus erythematosus (SLE). Although in some cases this may be the result of intercurrent fibromyalgia, mood disorder or untreated metabolic syndrome, in many cases the cause is unclear. The aim of this study was to investigate the relationship between fatigue and red cell distribution width (RDW), a measure of variability in erythrocyte size and volume.
METHODS:
A total of 225 patients were recruited from three clinics in England and Australia. Patients completed the Functional Assessment of Chronic Illness Therapy (FACIT) Fatigue Score or 12-item Short Form survey (SF-12) to measure fatigue, which was compared with RDW and haemoglobin. In a subgroup of 72 patients, markers of disease activity were also assessed for correlation with fatigue using univariate and multivariate analysis with fatigue as the dependent variable.
RESULTS:
In all three groups, significant correlations between fatigue and RDW were observed (p<0.001; p=0.02; p<0.001 respectively) and this was preserved in multivariate analysis. There was no correlation between fatigue and haemoglobin in two groups (with the correlation between RDW and fatigue remaining significant in non-anaemic patients in the third group). In subgroup analysis, fatigue was not associated with any measures of disease activity.
CONCLUSIONS:
We report a reproducible, statistically significant association between RDW and fatigue levels in a diverse population of patients with SLE. The findings of this study raise the possibility of a potential novel biological basis for fatigue in those in whom there is a lack of an alternate explanation.

Paywall, https://www.clinexprheumatol.org/abstract.asp?a=13852
No Sci hub access at time of posting.

 

[Hutan]

Interesting - that red blood cell size variation might be related to fatigue.

From wikipedia, Red Blood Cell Distribution Width is a measure of the range of variation in red blood cell volume. A high variation means that there is a wide range of sizes.

Usually red blood cells are a standard size of about 6-8 μm in diameter. Certain disorders, however, cause a significant variation in cell size....Normal reference range of RDW-CV in human red blood cells is 11.5-14.5%.

Some kinds of anaemia produce a high RDW; deficiencies of Vitamin B12 and folate can produce a kind of anaemia where RDW is commonly elevated. But it looks at though, in this study, they found some evidence in lupus patients that, even in non-anaemic patients, fatigue was related to RDW. But that RDW wasn't related to measures of lupus disease activity.

Given that RDW is part of the standard complete blood count (as RDW, RDW-CV, RCDW, RDW-SD), I presume if people with ME/CFS had high RDW's it would have been noticed.

For what it's worth, my RDW's and those of my son have been consistently normal, even tending towards the low end of normal.

 

[Arnie Pye]

Given that RDW is part of the standard complete blood count (as RDW, RDW-CV, RCDW, RDW-SD)

I live in the UK. The NHS has never measured my RDW. I've only ever had it measured as part of blood tests I've paid for privately.

My RDW has varied from being in the top 10% of the range or over the range between 2013 - 2015 (I have no data before that), and then for some unknown reason it dropped a lot in 2016 and has stayed in the bottom half of the range ever since. In 2018 it was 8% of the way through the range. I don't know whether a low in range level is good or bad.

 

[Hutan]

Well, actually I just assumed that it was a positive correlation - higher RDW=higher fatigue. Looking now, the abstract doesn't actually say that it is a positive correlation.

Maybe they found that lower RDW was correlated with fatigue. I just assumed very uniformly sized red blood cells was a good thing, but googling, maybe it isn't.

 

[arewenearlythereyet]

I think macrocytic anaemia is large blood cells and these are associated with b12./folate deficiency ...I think the fatigue is to do with haemoglobin concentration and distribution but I might be foggy on that. Low iron anaemia produces smaller red blood cells which also causes fatigue due to less haemoglobin. Low iron would show up with ferritin results.

When I’ve been tested my rbc count has been low which brings down haemoglobin and haematocrit, but other blood tests normal (as defined by the reference ranges)