Which mineral pairing is typically assessed to evaluate bone metabolism disorders?

• A. Sodium and potassium
• B. Magnesium and zinc
• C. Calcium and phosphorus
• D. Chloride and bicarbonate

Answer: (C)

Calcium and phosphorus are the minerals most closely tied to bone metabolism. Bone is made of a mineral matrix of calcium phosphate (hydroxyapatite), so the balance and levels of these two minerals reflect how actively bone is being formed or resorbed. Hormones like parathyroid hormone and vitamin D regulate their levels, and kidney function also influences phosphorus handling; measuring calcium and phosphorus together provides insight into disorders that affect bone turnover, such as osteoporosis, osteomalacia, or CKD-related bone disease. Other mineral pairs listed play important roles in general physiology, but they are not the primary indicators used to assess bone metabolism status.