Pica : It is well documented symptom but unexplainable. Pica is a habitual ingestion of unusual substances, the most common of which is eating mud or clay (Geophagia), laundry starch (amylophagia) and ice (pagophagia). Pica usually is the manifestation of iron deficiency and is relieved when condition is treated. Clay can behave in the gut as an exchange resin and can interfere with iron absorption.

Changes in Epithelial cells : These include koilonychia, platynychia, angular stomatitis, atrophic glossitis and mucosal changes in the stomach and small bowel leading to mucosal web as seen in Plummer Wilson syndrome and Patterson Kelly syndrome which are rare in children.

Growth retardation : There is a marked reduction in weight in iron deficient children, though height seems to be unaffected.

Exercise intolerance : Maximum work capacity, work output and endurance are impaired in iron deficiency state. This is due to reduction in the mitochondrial enzyme alpha glycophosphatase dehydrogenase besides due to anemia. Study in Indonesia demonstrated a correlation between the work output of latex tapper and hemoglobin concentration. Work output as significantly less (19%) from tappers with iron deficiency anemia than from non-anemic tappers. Similarly another study found a significant decrease in the area of ground cleared of weeds by anemic laborers as compared with their non-anemic counterparts.

The study done at Sri Lanka demonstrated a significantly smaller work output by anemic tea-pickers. In some of the studies work output increased significantly following correction of anemia by administration of iron.

Behavioral changes : These changes occur due to diminished activity of aldehyde oxidase, required for serotonin catabolism, thus leading to increased levels of serotonin and 6-hydroxynidole compounds. MAO, which is also required for catabolism of catecholamine, is also reduced. Reduced attention span, irritability, decreased scholastic performance, poor academic achievement and conduct disorders occur in these iron deficient children.

In Egypt and Java, deficiency in the mental performance of school children was reversible with the treatment. In study of iron deficiency in the rat, depletion of total non-heme iron and ferritin iron in the brain established shortly after the time of weaning, could not be reversed inspite of continuous supply of iron from that time until adult life. Study done by Dalmann et al have shown lower mental and psychomotor development index score significantly lower than control infants. Anemic infants failed specifically in language capabilities, body balance, co-ordination skills when compared with control. Iron deficiency affects attention span and memory control rather than information processing and retrival. Webb and Oski also have found poor scholastic performance in anemic students. Gopaldas & associates noted substantial improvement in cognitive function in anemic children after treatment with iron.

Altered host response : Iron deficiency affects both cell mediated as well as humoral immunity, though phagocytic activity may be normal. Killing of E.coli and Staph. aureus is reduced. In contrast, some studies state that immunity is enhanced in iron deficient state. This is due to increased unsaturated transferrin, which inhibits bacterial growth, and hence high dose IV iron therapy could be harmful in such cases. However oral iron therapy only minimally changes saturation of transferrin and hence practically it does not have any adverse effect on incidence of infection. In several studies, results show that infants who receive iron supplementary formulae have fewer episodes of respiratory and gastrointestinal infections than those who receive unsupplemented formula.