Iron needs during adolescence

The figure on the left is based on a representative boy whose peak adolescent growth is at 13.5 years, near the average in the United States. Iron needs peak sharply during the growth spurt but decline rapidly thereafter. Sexual maturation (progression from Tanner stages 2 to 5) begins approximately 2 years before peak growth; this signals the period of greatest iron needs. The figure on the right is based on a representative girl whose peak growth is at 11.5 years, near the average in the United States. Although iron needs in girls rise to a maximum during peak growth, they remain high subsequently since the need to replace menstrual iron loss begins approximately 1 year after peak growth. Because of the ongoing iron loss, the total iron requirement during adolescence is higher for girls than for boys. 
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