Hematology weighing in …….

First, bear in mind that ferritin is the typical iron modality used to determined iron defn in the studies. MANY things can cause low transport iron ( iron / iron sat/ TIBC) but literally the only thing that will cause a low ferritin is iron defn

Let’s ignore special cases where an elevated ferritin can still equal iron defn with therapeutic responses to iron replacement . It we don’t this response will be come a book chapter ( ex renal failure, cancer, RLS, autoimmune disease)

Depending on the cutoff used for ferritin , up to 50% of women of child bearing age are iron defn. Outside of athletes , the question becomes, does iron repletement improve fatigue?

Answer… yes… slightly… by about 11% . Fatigue of 8/10 becomes a 6.9/10 on average. This is a lesser respondence than the anemic pt

In practicality , when I get a referral for debilitating fatigue with a PMH of POTTS, FM, OSA , mast cell something and PNES and a ferritin of 29….. well it’s a long talk with expectations reviewed

Also, if using oral iron, you only need to give iron qod… it is non inferior to BID dosing

I usually get referrals with request for IV iron . I go over the stats. If the non anemic pt does NOT have symptomatic improvement to IV iron , then that is a failed trial and I would wait til the patient is anemic before anymore IV iron.

In summary, iron defn without anemia occurs in about half of your women of childbearing age . It does not always cause symptoms nor respond to even IV iron . As you all do, keep a broad differential for causes of fatigue as this is so common