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Abstract: SA-PO176

Intact PTH Remains a Good Marker of Bone Turnover in Disorder of Bone and Mineral Metabolism in CKD

Session Information

Category: Bone and Mineral Metabolism

  • 402 Bone and Mineral Metabolism: Clinical

Authors

  • Coutinho, Luiz Alberto soares de araújo, Universidade Federal de Pernambuco, Recife, PE, Brazil
  • Gueiros, Jose Edevanilson, Universidade Federal de Pernambuco, Recife, PE, Brazil
  • Vaz, Julia Braga, Universidade Federal de Pernambuco, Recife, PE, Brazil
  • Russo, Eduarda Cerqueira, Universidade Federal de Pernambuco, Recife, PE, Brazil
  • Jorgetti, Vanda, Universidade de Sao Paulo, Sao Paulo, São Paulo, Brazil
  • Gueiros, Ana Paula, Universidade Federal de Pernambuco, Recife, PE, Brazil
Background

Bone biopsy (BB) is the gold standard for diagnosing renal osteodystrophy (RO). Given its invasive nature and low availability in most centers, biomarkers are most commonly used to diagnose and guide the treatment of RO. Among these biomarkers, intact parathyroid hormone (iPTH) and alkaline phosphatase are widely used, but their predictive value is still questioned. There are few available data comparing BB and bone metabolism biomarkers. The aim of this study was to assess the ability of iPTH and total alkaline phosphatase (TAF) to predict bone turnover in hemodialysis (HD) patients.

Methods

This was a retrospective cross-sectional study in a single center. The medical records of 250 patients who underwent BB from April 2004 to September 2021 were reviewed. Clinical and laboratory data: age, sex, time on HD, iPTH and TAF (due to methodological differences, it was expressed in the number of times it was above the upper limit of normal; xTAF). According to bone turnover, patients were divided into two groups: High turnover, represented by patients with a histological diagnosis of osteitis fibrosa and mixed disease, and Low turnover, comprising those with adynamic bone disease and osteomalacia. To assess iPTH and TAF as predictors of bone turnover, univariate and multivariate analyzes were performed and an ROC curve was produced.

Results

The median age of patients was 48 years, 57.6% were females, and had been on HD for a median time of 9 years. Univariate analysis: iPTH (OR 1.01, 95% CI 1.00-1.01; p<0.001); xTAF (OR 2.83, 95% CI 1.78-5.18; p<0.001); Multivariate analysis: only iPTH was significant (OR 1.01, 95% CI 1.0-1.01; p < 0.001). The produced ROC curve demonstrated an area under the curve of 0.9414 for iPTH, with 368 pg/mL as the best cut-off point to discriminate between high and low bone turnover (accuracy 87%, sensitivity 84%, specificity 100%). For xTAF, the area under the curve was 0.782, and the best discriminatory cut-off point for turnover was 1.16 TFA (accuracy 70%, sensitivity 69%, specificity 73%).

Conclusion

Our results have demonstrated that iPTH represents a good marker of bone turnover and may be used in clinical practice to discriminate between high and low turnover.