Pedemy All toolsTap the age, then type the CBC. The page says whether the child is anemic and microcytic, which way the indices point, what to test next and the iron dose in mg and mL.
This tool reads a child’s complete blood count for the two common causes of small red cells: iron deficiency and thalassemia trait. Tap the age band, then enter hemoglobin, MCV, red cell count and RDW. Anemia is defined by the WHO 2024 hemoglobin cutoffs: under 10.5 g/dL at 6–23 months, 11.0 at 2–4 years, 11.5 at 5–11 years, 12.0 at 12–14 years, and 12.0 for girls or 13.0 for boys aged 15 and over. Microcytosis uses the lower MCV limits for age from Nathan and Oski’s reference values, from 70 fL in toddlers to 78 fL in teens.
The Mentzer index (MCV divided by red cell count) above 13 points to iron deficiency and below 13 to thalassemia trait; a high RDW also favors iron deficiency. Ferritin confirms it: the 2026 AAP clinical report treats a ferritin of 20 ng/mL or less in young and school-aged children, and 30 ng/mL or less in adolescents, as iron deficiency. Ferritin rises with infection and inflammation, so the tool flags results that may be falsely normal. A high reticulocyte count switches the work-up to blood loss or hemolysis.
For iron deficiency the tool gives the AAP 2026 oral iron dose — 3 mg/kg of elemental iron once daily, or 65 mg for adolescents (the tool also uses 65 mg as a practical cap for heavier children) — in mg and in mL of ferrous sulfate drops (15 mg iron per mL) and elixir (44 mg per 5 mL), with the expected response at 1 month and the 3-month plan. It covers milk intake, lead testing, hemoglobin electrophoresis and its limits in alpha-thalassemia trait, family testing, and red flags such as hemoglobin under 7 g/dL or other low blood counts.
Both cause small red cells. Iron deficiency usually has a high RDW, a lower red cell count and a Mentzer index (MCV ÷ RBC) above 13. Thalassemia trait often has a normal RDW, a normal or high red cell count and a Mentzer index below 13. These are clues only; confirm with ferritin and, if iron is normal, hemoglobin electrophoresis.
The 2026 AAP clinical report uses a ferritin of 20 ng/mL or less in young and school-aged children and 30 ng/mL or less in adolescents and menstruating individuals. WHO 2020 uses lower cutoffs of under 12 and 15. Ferritin is raised by infection and inflammation, so a normal value during illness does not rule out iron deficiency.
The AAP 2026 report recommends ferrous sulfate 3 mg/kg of elemental iron once daily for children and 65 mg once daily for adolescents. Ferrous sulfate drops contain 15 mg of iron per mL. Recheck at 1 and 3 months; continue the same dose for at least 3 months, and 3 months more if ferritin is still under 20 ng/mL.
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