Iron Therapy for Autosomal Dominant Hypophosphatemic Rickets: A Pilot Project.

Inclusion Criteria: * FGF Mutation in either Arginine 176 or arginine 179 * able and willing to provide consent or have a parent that is able/willing to consent, if a minor * either serum iron \<50mcg/dl (regardless of phosphate or intact FGF23 concentration); or iron between 500 and 100mcg/dl with serum phosphorus value below 3.0mg/dl for adults or less than or equal to 0.5 mg/dl the lower limit of normal for age in children and intact FGF23 about 30pg/ml * age \>2 years * May be receiving treatment with phosphate and calcitriol, but must be willing to undergo dose adjustments by the investigators if iron resolves the phosphate wasting defect. Exclusion Criteria: * malignancy within the last 5 years, except treated squamous or basal cell skin carcinoma * terminal illness/hospice. * severe end-organ disease, e.g. cardiovascular, pulmonary, etc, which may limit ability to complete study. estimated GFR \<45ml/min/1.73m2, calculated using MDRD formula for adults or modified Schwartz equation for children * pregnancy or plan on becoming pregnant