Estrogen treatment in tall girls increases the levels of active vitamin D in the body. This was shown in a study where 16 girls took estrogen to limit their height. The girls had higher levels of 1,25-dihydroxyvitamin D after treatment. The ratio of another form of vitamin D decreased. A protein that carries vitamin D in the blood also increased. The increase in active vitamin D may be due to the rise in this protein or estrogen's effect on a specific enzyme in the kidneys.