Vitamin D And Bone Disease

Vitamin D And Bone Disease

Write a note on pathologic changes in vitamin D deficiency.
Answer:

Following are the pathologic changes in vitamin D deficiency:

vitamin D deficiency In children

Vitamin A deficiency symptoms

In children Skeletal Changes

These are as follows:

• Craniotabes is the earliest bony lesion occurring due to small round unossified areas in the membranous bones of the skull, disappearing within 12 months of birth. The skull looks square and box-like.
• Harrison’s sulcus appears due to the indrawing of soft ribs on inspiration.
• The rachitic rosary is a deformity of the chest due to cartilaginous overgrowth at the costochondral junction.
• Pigeon chest deformity is the anterior protrusion of the sternum due to the action of respiratory muscles.
• Bow legs occur in ambulatory children due to weak bones of the lower legs.
• Knocked knees may occur due to enlarged ends of the femur, tibia, and fibula.
• Lower epiphyses of the radius may be enlarged.
• Lumbar lordosis is due to the involvement of the spine and pelvis.

In children Biochemical Changes

These are as follows:

• Lowered levels of active metabolites of vitamin D.
• Plasma calcium levels are normal or slightly low.
• Plasma phosphate levels are lowered.
• Plasma alkaline phosphatase is usually raised due to osteoblastic activity.

vitamin D deficiency In adults

Osteomalacia is the adult counterpart of rickets in which there is the failure of mineralization of the osteoid matrix. It may occur following dietary deficiency, poor endogenous synthesis of vitamin D, or as a result of conditioned deficiency.

In adults Clinical Features

• Osteomalacia is characterized by:
• Presence of muscular weakness
• Presence of vague bony pains
• Fractures following trivial trauma
• Incomplete or greenstick fractures
• Looser zones or pseudofractures at weak places in bones.

Night blindness due to vitamin A

In adults Histopathology

• H&E stained tissue shows widened and thickened osteoid seams.
• There is decreased mineralization between osteoid and bones.
• Increased osteoclastic activity is also appreciated.
• Fibrosis of bone marrow is present.

In adults Biochemical Changes

These are:

• Normal or low serum calcium levels
• Plasma phosphate levels lowered
• Raised serum alkaline phosphatase due to increased osteoblastic activity.