Rank the evidence and choose the action

For the guided case, rank depleted-store iron deficiency above inflammation and a thalassemia-pattern differential because the low ferritin, low TSAT, increased TIBC, increased RDW, and smear align together. Normal CRP reduces one confounder but does not prove that inflammation is absent. The relatively ordinary RBC count and absence of target-cell predominance argue against, but do not eliminate, a thalassemia-pattern differential.

Do not diagnose thalassemia from a discrimination index. If CBC, smear, and iron context leave a thalassemia-pattern differential, select hemoglobin analysis according to local reflex criteria and authorization. Recent transfusion can create dimorphism and obscure RBC-index and hemoglobin-analysis interpretation, while iron deficiency can coexist with a hemoglobinopathy and alter interpretation.

Before a bounded comment is released, obtain relevant history for recent transfusion, iron therapy, pregnancy, inflammation, and renal disease when available. Verify that controls, reportable range, reference intervals, and local review policy support the released result. Local policy defines the analyzer, reagent lot, calibrator, software, turnaround time, delta check, escalation pathway, and comment wording.