Metabolic Bone Diseases
In bone scurvy affects by
|A||Decreasing mineralization of bone|
|B||Less formation of osteoid matrix|
|C||Affection of the zone of provisional calcification only|
|D||Loss of calcium from the mineralized matrix of bone|
Less formation of osteoid matrix
In the synthesis of collagen, ascorbic acid is required as a cofactor for prolyl hydroxylase and lysyl hydroxylase.
b. These two enzymes are responsible for the hydroxylation of the proline and lysine amino acids in collagen.
c. Hydroxyproline and hydroxylysine are important for stabilizing collagen by cross-linking the propeptides in collagen. Defective collagen fibrillogenesis impairs osteoid formation in bone.
d. Musculoskeletal abnormalities include --Osteolysis, joint space loss, osteonecrosis, osteopenia, and/or periosteal proliferation.
e. Trabecular and cortical osteoporosis is common. Children experience severe lower limb pain related to subperiosteal bleeding.
f. Laboratory tests show nonspecific abnormalities including anemia and low levels of cholesterol and albumin.
g. The finding of a serum ascorbic acid level lower than 2.5 mg/l confirms the diagnosis. Vitamin C supplementation ensures prompt resolution of the symptoms.