William Aird/X

Apr 12, 2026, 13:42

William Aird: Anemia of Inflammation Not Just a Trade-Off but a Possible Compensation

William Aird, Professor of Medicine at Harvard Medical School, shared a post on LinkedIn:

”Anemia of inflammation: trade – off or adaptation?

We usually think of anemia of inflammation as a cost.

Iron is sequestered to limit microbial growth, and red cell production falls as a consequence.

But there may be another way to look at it.

The acute phase response increases plasma viscosity, driven in part by fibrinogen.
At the same time, hematocrit falls.

Since hematocrit is a major determinant of whole-blood viscosity, even a modest reduction may offset the rheologic effects of inflammation.

In other words:

Two observations are at least consistent with this idea:

In critical care, restrictive transfusion strategies (hemoglobin ~7 g/dL) perform as well as, or better than, more liberal approaches.
And in anemia of inflammation, hemoglobin levels tend to plateau rather than fall indefinitely, often remaining in the 7–10 g/dL range unless another process is present.

There appears to be a floor.

Not necessarily just a trade-off.
Possibly a compensation.”

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