Autosomal dominant hypophosphatemic rickets (ADHR) is a rare hereditary disease in which excessive loss of phosphate in the urine leads to poorly formed bones (rickets), bone pain, and tooth abscesses. ADHR is caused by a mutation in the fibroblast growth factor 23 (FGF23). ADHR affects men and women equally; symptoms may become apparent at any point from childhood through early adulthood. Blood tests reveal low levels of phosphate (hypophosphatemia) and inappropriately normal levels of vitamin D. Occasionally, hypophosphatemia may improve over time as urine losses of phosphate partially correct.
