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Abstract: PO0385

Diagnostic Accuracy of Static Bone Histomorphometry Parameters to Define Low Bone Turnover

Session Information

Category: Bone and Mineral Metabolism

  • 402 Bone and Mineral Metabolism: Clinical

Authors

  • Hughes-Austin, Jan M., University of California San Diego, La Jolla, California, United States
  • Pereira, Renata C., University of California Los Angeles, Los Angeles, California, United States
  • Jorgetti, Vanda, Universidade de Sao Paulo, Sao Paulo, São Paulo, Brazil
  • Salusky, Isidro B., University of California Los Angeles, Los Angeles, California, United States
  • Ix, Joachim H., University of California San Diego, La Jolla, California, United States
Background

Tetracycline labeling for bone biopsy allows pathologists to measure the pace of new bone production, which is critical to defining bone pathology in CKD. In the setting of clinical fractures, bone tissue is available, but tetracycline labeling is not possible. Therefore, we sought to determine the diagnostic accuracy of static measures of bone turnover relative to that measured by tetracycline in CKD patients undergoing iliac crest biopsy and histomorphometry.

Methods

We evaluated 147 individuals ages 12.4 ±8.9 who had undergone iliac crest bone biopsy with tetracycline labeling for clinical indications of CKD-MBD. Using the tetracycline labels under florescence, we defined bone formation rate relative to bone surface (BFR/BS) < 8 (normal range 8-73) as our gold standard to define low bone turnover. A blinded investigator used light microscopy without fluorescence to measure static bone turnover parameters. We then compared the area under the ROC curve (AUC), sensitivity, and specificity of each bone turnover parameter with low turnover based on tetracycline using the Youden J Index, which is the point on the ROC curve farthest from line of equality that maximizes sensitivity and specificity.

Results

Among the 147 biopsies, 35 (24%) had low bone turnover based on tetracycline. Weevaluated 5 parameters available by static bone microscopy, among which Osteoblast Surface relative to Bone Surface (Ob.S/BS), Osteoclast Surface relative to Bone Surface (Oc.S/BS), and Osteoid Volume to Bone Volume (OV/BV) had the highest AUCs for low bone turnover based on tetracycline labeling. Using the best cut-offs from the AUC curves, a %Ob.S/BS of 82% had a sensitivity and specificity of 80% and 75% for low bone turnover.

Conclusion

Static measures of bone turnover have high sensitivity and specificity for identifying low bone turnover defined by tetracycline labeling at the iliac crest in CKD patients. Bone tissue without tetracycline labeling may be useful clinically to define bone turnover.

Funding

  • Other NIH Support