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Abstract: TH-PO568

Are Bone Biopsies Needed Only in Patients with PTH Results Outside the KDIGO Target Range?

Session Information

Category: Bone and Mineral Metabolism

  • 402 Bone and Mineral Metabolism: Clinical

Authors

  • Rao, Madhumathi, University of Kentucky, Lexington, Kentucky, United States
  • Lima, Florence, University of Kentucky, Lexington, Kentucky, United States
  • Faugere, Marie-Claude M., University of Kentucky, Lexington, Kentucky, United States
  • Malluche, Hartmut H., University of Kentucky, Lexington, Kentucky, United States
Background

The 2017 KDIGO guideline update for chronic kidney disease - mineral bone disorder (CKD-MBD) in CKD-5D recommends that parathyroid hormone (PTH) levels be maintained 2 to 9 times upper normal for the assay (150-600pg/mL). There is no information on histologic bone abnormalities within vs. outside the KDIGO target PTH range.

Methods

We analyzed 142 bone biopsies done between 2004-2019 on CKD-5D patients performed for a variety of indications (fracture, hypercalcemia, osteoporosis, calciphylaxis and prior to parathyroidectomy (PTX)). The objective was to examine to what degree bone biopsies are helpful in management of patients with PTH levels outside or within the KDIGO target range.

Results

Mean age was 49±15 years, 46% were male and 63% white. Median (IQR) PTH was 776 (333-1348) pg/mL; there was a weak inverse relationship with age (r=-0.2, p<0.05), but no difference by race. Most of the biopsies (56%) were performed in patients with PTH levels >600 pg/mL (PTH>600 group); 33% of the biopsies were done in patients within the target KDIGO range (KDIGO target PTH group) and 11% in patients with PTH<150 pg/mL (PTH<150 group).
The KDIGO target PTH group showed severe hyperparathyroid bone disease (HPTBD) with high to very high bone turnover (BTO) in 69%, mild to moderate HPTBD in 21% and low turnover bone disease (LTBD) in 10%. The PTH<150 group showed either LTBD or mild to moderate HPTBD. Patients within and below the KDIGO guideline were over twice as likely to show low bone volume on their biopsy (OR 2.2 95%CI 1.03-4.7). Anti-resorptive treatment was recommended in 7 patients in the KDIGO target PTH group, and anabolic therapy in 4 patients in the PTH<150 group. In the PTH>600 group, the concordance with severe HPTBD and high to very high BTO on biopsy was 92%, with moderate HPTBD in 8%; 44% subsequently underwent PTX.

Conclusion

Patients with PTH levels within the KDIGO target range show heterogeneity in their bone abnormalities with both HPTBD and LTBD, and bone loss. Contrary to current practice, these patients may be a unique risk group needing bone biopsy for targeted management of CKD-MBD. While bone biopsies are clearly also needed in patients with PTH levels below target, the procedure adds relatively little information in patients with levels above target.