A 74-year-old man with chronic renal failure has had repeated pathological fractures. Laboratory analysis reveals:
Serum calcium: 6.3 mg/dL
Serum phosphate: 4.7 mg/dL
Parathyroid hormone: 750 pg/mL
Which of the following most likely contributes to the pathogenesis of this man’s bone disease?
(A) Decreased 1,25-dihydroxycholecalciferol production
(B) Decreased 25-hydroxyvitamin D production
© Decreased calcium intake
(D) Decreased vitamin D2 intake
(E) Decreased vitamin D3 intake