Guided case: microcytosis with limited response

The guided case has hemoglobin 8.4 g/dL, hematocrit 27.0%, RBC 3.55 × 10^12/L, MCV 76 fL, RDW-CV 18.6% (above the 14.5% upper interval), and ARC 35.5 × 10^9/L. Under the stated same-specimen, pretreatment timing assumption, ARC is inadequate for this degree of anemia. Smear review of 1,000 RBCs in the optimal monolayer finds hypochromic microcytes and anisocytosis; no schistocytes are identified under this declared review convention.

Reticulocyte percentage is 1.0%. Corrected percentage = 1.0 × 27 ÷ 45 = 0.60%. With hematocrit 27%, maturation factor 2.0 applies in this instructional convention, so RPI = 0.60 ÷ 2.0 = 0.30, below 2 and consistent with inadequate response. This calculation is instructional, not universal.

Ferritin 8 ng/mL and TSAT 5% support restricted iron availability. Because the iron studies are complete, the next defensible action is to obtain the clinical source/absorption history; if it is unavailable, state that missing information rather than order another iron-domain test.