True about metastatic calcification aEUR’
**Core Concept**
Metastatic calcification is a pathological process where calcium salts deposit in previously healthy tissues, usually due to hypercalcemia. It is distinct from dystrophic calcification, which occurs in damaged or necrotic tissues. Metastatic calcification can be caused by various conditions, such as hyperparathyroidism, vitamin D toxicity, or malignancies.
**Why the Correct Answer is Right**
Metastatic calcification occurs when serum calcium levels exceed the normal range, leading to the precipitation of calcium salts in tissues. This can happen in conditions like hyperparathyroidism, where excessive parathyroid hormone (PTH) secretion leads to increased calcium resorption from bones and increased renal calcium reabsorption. The high calcium levels can then precipitate out of solution and deposit in tissues, causing damage. The lungs, kidneys, and blood vessels are common sites for metastatic calcification.
**Why Each Wrong Option is Incorrect**
* **Option A:** This is not a correct statement about metastatic calcification. While dystrophic calcification does occur in damaged tissues, it is distinct from metastatic calcification, which occurs in previously healthy tissues due to hypercalcemia.
* **Option B:** This option is incorrect because dystrophic calcification is a different process altogether, occurring in damaged or necrotic tissues, whereas metastatic calcification occurs in healthy tissues due to hypercalcemia.
* **Option C:** This is not a correct statement about metastatic calcification. While vitamin D toxicity can lead to hypercalcemia, it is not a direct cause of metastatic calcification. Instead, it contributes to the underlying hypercalcemia that can lead to metastatic calcification.
**Clinical Pearl / High-Yield Fact**
To remember the difference between metastatic and dystrophic calcification, think of it as "metastatic calcification" being caused by "metabolic" disturbances (hypercalcemia) and "dystrophic calcification" being caused by "tissue" damage.
**Correct Answer:** D.