A 60-year-old woman with chronic kidney disease (stage 4, eGFR 22 mL/min/1.73m²) presents with diffuse bone pain and proximal weakness. Serum calcium is low-normal, phosphate is elevated, PTH is markedly elevated, and alkaline phosphatase is moderately elevated. X-ray shows subperiosteal resorption in the radial aspect of the middle phalanges. The underlying bone disease is best classified as:
- A High-turnover bone disease (osteitis fibrosa cystica) ✓
- B Osteomalacia due to defective mineralization
- C Low-turnover (adynamic) bone disease
- D Mixed uremic osteodystrophy with predominant osteomalacia
Correct answer: A. High-turnover bone disease (osteitis fibrosa cystica)
Explanation
Secondary hyperparathyroidism from CKD causes high-turnover bone disease called osteitis fibrosa cystica. Elevated PTH drives increased osteoclastic resorption. Subperiosteal resorption along the radial aspect of the middle phalanges is the classic radiographic sign. Adynamic bone disease would show low PTH and low ALP. Osteomalacia in CKD is less common and would show predominant mineralization defect.
Reference: Harrison's Principles of Internal Medicine, 20th ed.
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Written and medically reviewed by the StethoPrep medical team.