**Question:** Hypervitaminosis of which of the following will cause bony abnormalities - a) Vitamin A (Vit. Ab), b) Vitamin D (Vit. Dc), c) Vitamin C (Vit. Cd), d) Vitamin E (Vit. De), e) Vitamin K (Vit. Ke)?

**Core Concept:** Vitamin D plays a crucial role in calcium and phosphate homeostasis, which is essential for bone mineralization and overall skeletal health. Inadequate or excessive intake of Vitamin D can lead to hypervitaminosis D, a condition characterized by abnormal bone mineralization.

**Why the Correct Answer is Right:** Hypervitaminosis D results from excessive intake of Vitamin D, which leads to increased calcium absorption in the intestine. Calcium overload in the body can cause bone pain, osteoporosis, and ultimately, bony abnormalities. Additionally, Vitamin D is involved in the regulation of phosphorus levels, contributing to the development of hyperphosphatemia in hypervitaminosis D.

**Why Each Wrong Option is Incorrect:**

A. Vitamin A (Hypervitaminosis A) primarily affects the eyes, liver, and kidneys, leading to visual disturbances, hepatorenal toxicity, and bone abnormalities are less common.

B. Vitamin C (Hypervitaminosis C) primarily affects wound healing, causing impaired collagen synthesis and bleeding disorders. Bone abnormalities are less common.

C. Vitamin C (Hypervitaminosis C) primarily affects wound healing, causing impaired collagen synthesis and bleeding disorders. Bone abnormalities are less common.

D. Vitamin E (Hypervitaminosis E) primarily affects red blood cell membrane integrity, leading to hemolysis and anemia. Bone abnormalities are less common.

E. Vitamin K (Hypervitaminosis K) primarily affects blood clotting, causing hemorrhage and bleeding disorders. Bone abnormalities are less common.

**Clinical Pearl:** The correct answer is Vitamin D (Hypervitaminosis D) because excessive intake of Vitamin D leads to impaired calcium and phosphorus excretion, causing hypercalcemia and hyperphosphatemia, respectively, ultimately resulting in bone abnormalities. These abnormalities are a result of Vitamin D's role in calcium and phosphate homeostasis, and its influence on bone mineralization.