Serum ferritin in Danish children and adolescents.

Serum ferritin concentrations were measured in 909 urban Danish schoolchildren (451 boys, 458 girls) 6 to 17 years old. The children had been randomly selected and served as an urban reference population. Geometric mean ferritin values were identical in boys and girls 6 to 15 years old, while 16- and 17-year-old boys had higher values than girls (P less than 0.01). There was a slight rise in mean ferritin values from 6 to 11 years, followed by a temporary fall during the subsequent adolescent growth period. Geometric mean ferritin values and significant differences were as follows: Children 6 to 11 years old (n = 335), 29 micrograms/l and adolescents 12 to 15 years old (n = 417), 26 micrograms (P less than 0.01): Adolescent boys 16 to 17 years old (n = 76), 32 micrograms/l and adolescent girls same age (n = 81), 24 micrograms/l (P less than 0.01). The frequencies of low ferritin values less than 10 micrograms/l (i.e. exhausted iron stores) were: Children 6 to 11 years old, 2.1%: Adolescents 12 to 15 years old, 5.0%: Adolescent boys 16 to 17 years old, 0.0%: Adolescent girls 16 to 17 years old, 11.1%. High ferritin values greater than 60 micrograms/l (i.e. large iron reserves) were observed in 6.2% of boys and 6.9% of girls.