Vitamin D-Resistant Rickets

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Some people, however, may suffer from rickets even if they get enough Vitamin D. This syndrome is also presented at an early age, and particularly when children start to walk. In these cases, a metabolite, or active form of Vitamin D, called 1,25 - dihydrocalciferol, is added as a dietary supplement, in addition to phosphate.

• X-linked dominant
• defect in renal tubular resorption of phosphate
• presents at 1 yr
• progressive limb deformities

X-ray:

• less severe changes than other rickets
• presents later

Dx features:

• family hx
• normal serum calcium
• marked hypophosphatemia (decreased PO4)
• no secondary hyperPTH