Treating Before Anemia — Non-Anemic Iron Deficiency, Symptom Recognition, and Completing the Diagnostic Picture

Freed discusses the evidence supporting treatment of iron deficiency before anemia develops, the symptom burden of non-anemic iron deficiency including fatigue, restless legs syndrome, and pica.

The clinical teaching that iron deficiency and anemia are inseparable — that one does not meaningfully exist without the other — has persisted in medical training despite more than 3 decades of evidence to the contrary. Iron is essential to mitochondrial function and cellular metabolism across virtually every tissue in the body, and iron deficiency can produce clinically significant symptoms well before red blood cell parameters become abnormal. The paradox is that symptom sensitivity to iron deficiency varies substantially and unpredictably between individuals: some patients experience profound fatigue and reduced exercise tolerance with no measurable anemia, while others present with a hemoglobin of 7.5 g/dL and describe only vague, mild worsening. This variability is not yet understood mechanistically, but its clinical implication is clear — the decision to treat iron deficiency should not be gated on the presence of anemia. It should be informed by the probability that a given patient will benefit from iron repletion, which depends on symptom burden, ferritin level, and clinical context.

3 symptom domains are particularly important for clinicians to recognize as iron-related and act on accordingly. The first is fatigue: randomized trials of IV iron versus IV placebo in nonanemic women with iron deficiency have demonstrated that iron repletion produces meaningful improvement in fatigue, independent of any change in hemoglobin. The second is restless legs syndrome, which is among the most consequential and underreported manifestations of iron deficiency — patients often do not seek care for it because they do not recognize it as a medical problem rather than an unchangeable feature of their lives, and iron deficiency as an etiology is frequently not considered. The third is pica, the craving for non-food substances, most commonly ice — a behavioral manifestation of iron deficiency with a probable evolutionary basis in the drive to obtain minerals from environmental sources. In severe cases, patients consume 4 or more large cups of ice per day and can sustain dental damage as a result; IV iron repletion typically resolves the craving within days. Together, these symptom domains represent a large population of patients whose quality of life is being significantly affected by iron deficiency that is neither recognized nor treated.

In this segment of the video discussion on iron deficiency anemia, Jason Freed, MD describes how he constructs the complete diagnostic picture beyond ferritin alone. Transferrin saturation (TSAT) is the most useful complementary test, particularly in patients with chronic kidney disease or chronic inflammatory disease in whom ferritin may be falsely elevated and a low TSAT identifies iron-deficient states that ferritin alone would miss. The CBC is interpreted not merely as a binary anemic or nonanemic result but as a longitudinal trend: hemoglobin is a highly stable physiologic parameter in the absence of disease, and a decline of 1 g/dL or more — even if the absolute value remains within the labeled normal range — is a clinically meaningful signal. Mean corpuscular volume (MCV) is similarly stable over time, and the teaching that iron deficiency anemia equals microcytic anemia is, by Freed's characterization, wrong — more than half of patients with iron deficiency anemia have a normocytic MCV by absolute criteria, but nearly all show a relative decline from their personal baseline. Freed frames the diagnostic approach not as identifying a threshold that definitively establishes disease, but as assembling evidence for the likelihood that a given patient will benefit from iron — a probabilistic framework that better reflects the clinical reality of this condition than any single cutoff. structural flaw in how laboratory reference ranges are constructed. Reference ranges are developed locally: each institution validates its own normal range by measuring a parameter in approximately 120 healthy individuals from the surrounding community and defining normal as the central 95th percentile of that distribution. This approach works reasonably well for most laboratory values, but it fails catastrophically for iron and ferritin in populations where iron deficiency is endemic. When two-thirds of premenopausal women are iron deficient, those women constitute the healthy reference population — and iron deficiency becomes enshrined as normal by the mathematics of the method itself. The consequence is visible in hemoglobin reference ranges: many laboratories use a lower limit of approximately 10.7 g/dL for women compared with 13.5 g/dL for men, a gap of nearly 3 g/dL that cannot be explained by the physiologic effects of testosterone alone, which accounts for approximately 1 g/dL of true sex-based difference. The remainder reflects under-recognized, under-treated iron deficiency that has been absorbed into the definition of normal.

In this video discussion on iron deficiency anemia, Jason Freed, MD, an assistant professor of medicine at Harvard Medical School, examines what the ASH draft guidelines — issued for public comment in 2025 — propose to address this problem. The draft recommends a ferritin cutoff of 30 µg/dL for general healthy adults, with consideration for a threshold of 50 µg/dL, representing a meaningful departure from the World Health Organization's longstanding cutoff of 15 µg/dL and from the local reference ranges most clinicians encounter in their electronic health records. Freed notes that the debate between 30 and 50 reflects a legitimate concern about over-medicalizing iron deficiency in asymptomatic individuals, but argues that for any patient presenting with a symptom attributable to iron deficiency — anemia, fatigue, restless legs syndrome — a ferritin below 50 µg/dL is an actionable finding. He emphasizes that correcting reference ranges at the health system level will ultimately require institutional advocacy and committee action, not just individual clinician awareness, and that the finalization of the ASH guidelines is a necessary prerequisite for that broader implementation effort to begin in earnest.