February 1988

Picture of the Month

Author Affiliations

Contributed from Children's Hospital Medical Center, Cincinnati, and the University of Cincinnati College of Medicine.

Am J Dis Child. 1988;142(2):191-192. doi:10.1001/archpedi.1988.02150020093038

Denouement and Discussion 

X-linked Dominant Hypophosphatemic Rickets 

Manifestations  Hypophosphatemic rickets is characterized by a primary defect of the reabsorption of filtered phosphate in the kidney, leading to chronic urinary phosphate wastage. This condition is also characterized by an altered vitamin D metabolism; serum 1,25-dihydroxycholecalciferol concentrations are paradoxically "low" for the degree of hypophosphatemia. Defective mineral metabolism leads to impaired mineralization, affecting both epiphyseal cartilage and osteoid tissue at the endosteal bone surface. Lower limbs are clinically and radiologically more affected by the rachitic process than are upper limbs. In contrast to acquired tumor-induced hypophosphatemic rickets, there is no proximal myopathy. Craniosynostoses have been described as complications of the disease but may be precipitated by treatment with 1,25-dihydroxycholecalciferol.Dentin defects (interglobular dentin) lead to a mottled appearance of the tooth surface. Dental abscesses that are not associated with caries or trauma are frequent complications. As a consequence of abnormal dentin formation, large, tubular

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