system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
A 58-year-old woman with type 2 diabetes mellitus comes to the physician because of generalized pain and muscle weakness. She suffered a nondisplaced left ulnar fracture 3 months ago after lifting a heavy crate of books. She has had progressively worsening renal function over the past 2 years but has not yet started hemodialysis. An x-ray of the left wrist shows a healing fracture in the ulna with thinned cortices. There are multiple transverse radiolucent bands adjacent to the fracture, surrounded by a thin sclerotic margin. This patient's findings are most likely due to the impaired production of which of the following substances?
assistant
1,25-dihydroxycholecalciferol