Serum ironNutrition library
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Serum iron
Serum iron measures circulating iron bound to transferrin — a snapshot of iron supply, not stores.
Low serum iron with low transferrin saturation supports iron-deficiency workup; ferritin confirms stores. Values fluctuate with recent meals, inflammation, and diurnal rhythm.
How to read it
Pair with ferritin, transferrin saturation, and MCV. Dietary iron and absorption modifiers in the app model absorbed iron separately from this lab marker.
Trimester context
| Stage | For the mother | For the baby |
|---|---|---|
| First trimester | Early demand rises before haemoglobin falls — a low value may precede anaemia. | Placental iron transfer accelerates later in pregnancy. |
| Second trimester | Haemodilution and rising fetal demand often lower serum iron even when intake is adequate. | Fetal brain and liver iron accretion increases. |
| Third trimester | Optimise before delivery to reduce transfusion and fatigue risk. | Late-trimester accretion is highest. |