Talk:Red blood cell distribution width

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increased rdw is a transient phenomenon

I think the discussion could be improved by pointing out that rdw is increased whenever the average cell size is changing, that is, while there is a mix of sizes. When a condition that causes an abnormal mcv has become chronic, that is when it has lasted a long time, the rdw will decrease again, with the distribution centered on the new mcv. Thus chronic iron deficiency or chronic lead poisoning will have microcytosis - low mcv, but can have normal rdw. The rdw will increase when the condition, say iron deficiency begins, and will increase again when a chronic iron deficiency is treated and the cell population is returning to normal size.

--AJim (talk) 02:14, 20 January 2010 (UTC)[reply]

This is still not addressed. There is an article on microcytic anemia now; it includes a good differential, which includes the anemia of chronic disease. Again, chronic conditions are expected to have a narrow rdw, centered on a lower mcv.

An episode of fever will cause a transient drop in transferrin saturation, resulting in a period of microcytic cell production, and thus an increase of rdw during the approximately 120 days that cohort of cells persists in the circulation.

--AJim (talk) 17:16, 22 August 2012 (UTC)[reply]

Too high vs. too low

Maybe I'm missing something, but it doesn't seem like the article explains what it means if a patient's test result comes back as too high, versus what it means if the patient's test result comes back as too low. The article gives the normal reference range, but am I correct in assuming that a "too low" result would indicate a different problem than a "too high" result? Some clarification would be helpful. –BMRR (talk) 02:40, 3 December 2011 (UTC)[reply]

What I think you are missing is that rdw is based on a variance. I imagine that the variance in cell size is not normally reduced, so I think a "too low" rdw must be very rare. I can not think of a process that would lead to that result; the clinical significance is unclear to me.

--AJim (talk) 17:16, 22 August 2012 (UTC)[reply]