rickets type-1; pseudo-vitamin D deficiency

Pathology

• inadequate endogenous synthesis of 1,25(OH)2 vit D3
  • 1-alpha-hydroxylation deficiency
  • 25-hydroxylation deficiency
• reduced tubular resorption of phosphate
• hyperchloremic acidosis may occur

Genetics

• autosomal recessive
• associated with defects in CYP27B1

Clinical manifestations

• rickets begins < 2 years of age
• muscle weakness

Laboratory

• serum chemistries
  • serum Ca+2 is low (hyocalcemia)
  • parathyroid hormone (PTH) is elevated
  • alkaline phosphatase is elevated
  • phosphorous is variable
  • 1,25(OH)2vit-D3 is variable
  • hyperchloremia may occur
• urine chemistries
  • Ca+2 is diminished
  • aminoaciduria may occur
  • urinary cAMP increases normally in response to PTH infusion

Management

• calcitriol (observe for hypercalcemia)
• calcium 0.5-2.0 g QD

More general terms

• hereditary rickets

Database

• OMIM: https://mirror.omim.org/entry/264700
• OMIM: https://mirror.omim.org/entry/600081