Metastatic calcification due to hyperphosphatemia tends to involve which tissues?

• A. Skeletal bone
• B. Non-skeletal tissues
• C. Cardiac muscle
• D. Brain

Answer: (B)

Metastatic calcification happens when a high calcium-phosphate product in the blood causes calcium phosphate to deposit in normal, soft tissues rather than in bone. When phosphate is elevated, these precipitates tend to form in non-skeletal tissues, especially where the extracellular environment is relatively alkaline, such as the lungs, kidneys, gastric mucosa, and arterial walls. This pattern contrasts with dystrophic calcification, where calcium deposits occur in damaged or necrotic tissue, often within bone-adjacent areas. So, the tendency with hyperphosphatemia is toward non-skeletal soft tissues.