Normal serum bone markers in bisphosphonate-induced osteonecrosis of the jaws

We obtained serum bone markers and other relevant endocrine assays on 5 patients with osteonecrosis of the jaw (ONJ). The assays were C-telopeptide, N-telopeptide, bone-specific alkaline phosphatase, osteocalcin, intact parathyroid hormone, T3, T4, TSH, and Vitamin D 25 hydroxy. Diagnostic criteria for ONJ were those formulated by the American Association of Oral and Maxillofacial Surgeons. Four of our patients were women. Two had metastatic breast cancer and had been treated with zoledronic acid; one had also received pamidronate. Two others had osteoporosis and had been treated with daily alendronate. One man had metastatic prostate cancer treated with zoledronic acid. All patients had been withdrawn from bisphosphonate for at least 6 months. None were taking or had taken corticosteroids. None of the lesions had shown any significant healing and all were still causing the patients considerable distress. Yet the bone markers were within the normal range as measured in our laboratory, except for intact parathyroid hormone, which was slightly elevated in one case of metastatic breast cancer (177 pg/mL). Because the jaws have a greater blood supply than other bones, and a high bone turnover rate, bisphosphonates are highly concentrated in the jaws. This anatomic concentration of bisphosphonates might cause bisphosphonate-osteonecrosis to be manifested exclusively in the jaws and is consistent with our finding of normal serum bone markers in ONJ patients.