Which of the following is NOT a typical contributor to renal osteodystrophy in CKD?

• A. Phosphate retention
• B. Secondary hyperparathyroidism
• C. Low phosphate intake
• D. Vitamin D deficiency

Answer: (C)

In CKD, renal osteodystrophy arises from disturbances in mineral metabolism driven by reduced renal excretion of phosphate and impaired vitamin D activation. When the kidneys can’t excrete phosphate effectively, phosphate accumulates, which stimulates secondary hyperparathyroidism and increases bone turnover. At the same time, the diseased kidney cannot adequately activate vitamin D, leading to vitamin D deficiency and further decreases in calcium absorption, which feeds into the parathyroid-driven bone resorption. Among the factors listed, low phosphate intake would not typically contribute to renal osteodystrophy; phosphate retention, secondary hyperparathyroidism, and vitamin D deficiency are the usual culprits, whereas reducing phosphate intake would tend to lessen the mineral disturbances rather than cause them.