Bone affection in scurvy is due to
## **Core Concept**
Scurvy is a disease caused by vitamin C (ascorbic acid) deficiency, which plays a crucial role in the synthesis of collagen, a key component of connective tissue. The bone affection in scurvy is primarily related to the impaired collagen synthesis and osteoid formation.
## **Why the Correct Answer is Right**
The correct answer, , is related to the role of vitamin C in hydroxylation of proline and lysine residues during collagen synthesis. Vitamin C acts as a co-factor for prolyl hydroxylase and lysyl hydroxylase enzymes, which are essential for stabilizing and cross-linking collagen molecules. Without vitamin C, collagen synthesis is impaired, leading to defective osteoid formation and bone mineralization. This results in the characteristic bone changes seen in scurvy, such as osteoporosis, bone pain, and fractures.
## **Why Each Wrong Option is Incorrect**
* **Option A:** - This option is incorrect because, although important for various bodily functions, it is not directly related to the bone affection seen in scurvy.
* **Option B:** - This option is incorrect as it does not accurately describe the mechanism by which scurvy affects bone.
* **Option D:** - This option is incorrect because it does not relate to the biochemical or physiological changes occurring in scurvy that lead to bone affection.
## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that scurvy can present with a range of bone-related symptoms, including bone pain, swelling, and tenderness, as well as radiographic findings like the "Trümmerfeld zone" (a zone of rarefaction under the cortex) and "Frankel's line" (a dense line at the metaphysis). Early recognition and treatment with vitamin C can lead to rapid improvement.
## **Correct Answer: C. Impaired hydroxylation of proline and lysine.**