Talk:Red blood cell distribution width
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increased rdw is a transient phenomenon
editI 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)
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.
Too high vs. too low
editMaybe 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)
- 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.