Which groups need routine iron screening and how is deficiency diagnosed?

1. Who guideline authors explicitly flag for routine or prioritized screening

Pregnant people are a principal target for screening efforts: many quality‑improvement projects and expert groups focus on increasing screening and treatment in pregnancy, though some professional societies currently recommend screening only when pregnant patients have anemia (hemoglobin <11 g/dL) — a tension highlighted by implementation studies showing benefit from broader screening in pregnancy ^{[1] [2]}. Women of reproductive age, especially those with heavy menstrual bleeding, are repeatedly identified as high‑risk groups; several regional and expert consensus documents call for active case finding or preventive supplementation in these populations ^{[2] [3]}. Children, particularly infants and young children, remain a priority in older public‑health guidance and expert reviews because of developmental risks from iron deficiency ^{[8] [3]}. Patients with chronic diseases — notably chronic kidney disease and other inflammatory conditions — are specifically discussed as groups needing routine iron evaluation because inflammation changes test interpretation and iron needs ^{[4] [3]}.

2. Areas of disagreement and ongoing guideline work

Guideline writers disagree about who should receive routine screening and which laboratory thresholds to use. The American College of Obstetricians and Gynecologists (ACOG) currently recommends screening pregnant people only when anemia is present, while recent quality‑improvement programs and other expert consensuses argue for broader screening in pregnancy ^{[1] [2]}. The American Society of Hematology is actively drafting new diagnostic guidance with distinct recommendations for children, menstruating people, pregnant people, and adults with inflammation — reflecting unresolved questions and expected practice changes ^{[9] [10]}. This ongoing guideline activity indicates real uncertainty among specialty societies about universal versus targeted screening ^{[10] [9]}.

3. Tests clinicians use and the most cited diagnostic thresholds

Serum ferritin is the most commonly used single marker for iron deficiency. For patients with anemia and no inflammation, several authorities endorse a ferritin cutoff near 45 ng/mL to define iron deficiency; AGA systematic review–based guidance uses <45 ng/mL, and family‑physician summaries mirror that approach ^{[5] [6] [11]}. In settings of inflammation or chronic disease, higher ferritin thresholds are recommended because ferritin is an acute‑phase reactant; some sources use ferritin <100 ng/mL as diagnostic in inflamed patients, and combinations of ferritin 46–99 ng/mL plus TSAT <20% are used as alternative criteria ^{[6] [3]}. Transferrin saturation, soluble transferrin receptor, and C‑reactive protein are recommended adjuncts when inflammation or CKD may obscure ferritin results ^{[5] [7] [4]}.

4. What investigations follow a confirmed iron deficiency or iron‑deficiency anemia

When iron deficiency is confirmed — particularly in adults — gastroenterological evaluation is often advised to identify bleeding or malabsorption: screening for celiac disease and H. pylori, urinalysis, and upper/lower endoscopy in appropriate patients are repeatedly recommended by GI and general medicine guidelines ^{[12] [13] [11]}. Men and postmenopausal women with iron‑deficiency anemia are singled out for bidirectional endoscopy because of higher rates of GI malignancy found in some studies; the AGA recommends endoscopic evaluation in these groups ^{[5] [13]}.

5. Public‑health posture vs clinical nuance: implicit agendas and limitations

Population‑level recommendations (e.g., WHO support for iron supplementation in women in high‑prevalence settings) prioritize preventing deficiency where screening is limited, while specialty societies balance diagnostic specificity and resource use — hence differing advice on universal screening in pregnancy ^{[2] [1]}. Many of the sources are guideline drafts, consensus statements, or reviews that note limited or heterogeneous evidence for precise screening thresholds and the best screening strategy; ASH and KDIGO are revising guidance, showing evidence gaps remain ^{[10] [4] [9]}. Available sources do not mention a single universally accepted screening algorithm for asymptomatic nonpregnant adults — that lack explains the patchwork of recommendations (not found in current reporting).

6. Practical takeaways for clinicians and patients

Screen high‑risk groups: pregnant people (debate exists over universal vs targeted screening), women with heavy menstrual bleeding or reproductive‑age women in high‑prevalence settings, young children, and patients with CKD or chronic inflammatory disease ^{[1] [2] [3] [4]}. Use ferritin as the first‑line test; apply lower cutoffs (~<45 ng/mL) in noninflamed patients, higher cutoffs or combined criteria (ferritin 46–99 ng/mL + TSAT <20% or ferritin <100 ng/mL) when inflammation/CKD is present, and add TSAT, soluble transferrin receptor, or CRP as needed ^{[5] [6] [7]}. Expect changes: ASH, KDIGO, and other bodies are updating recommendations, so clinicians should watch for final guideline statements ^{[10] [9]}.

Limitations: this analysis synthesizes available guideline drafts, reviews, and consensus documents; evidence heterogeneity and active guideline development mean definitive, universal screening rules are not yet established in current reporting ^{[10] [9]}.