Hypophosphatemic rickets: still misdiagnosed and inadequately treated.

We studied the presentation and results of medical therapy in 25 children with sex-linked dominant hypophosphatemic rickets. The average age at diagnosis was 3.8 years. Reasons for the delay included misdiagnosis and failure to recognize the normal range of serum phosphorus levels in children. Early diagnosis and treatment (before age 1) was associated with normal alignment of the lower limbs. Combination therapy with phosphate and vitamin D2 improved growth and bone mineralization, but did not change the height percentile or limb alignment. Limited use of calcitriol (1,25-dihydroxyvitamin D3) was not helpful in the adolescent but was associated with limited height increase in two younger children. Early diagnosis and medical therapy should prevent bowing of the legs.