Abstract: SA-PO673
The Ability of Intact Parathyroid Hormone and Total Alkaline Phosphatase to Predict Bone Turnover in Patients with Renal Osteodystrophy
Session Information
- Bone and Mineral Metabolism: Clinical - II
October 27, 2018 | Location: Exhibit Hall, San Diego Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Bone and Mineral Metabolism
- 402 Bone and Mineral Metabolism: Clinical
Authors
- Gueiros, Jose Edevanilson, UFPE, Recife, Brazil
- Gueiros, Ana Paula, UFPE, Recife, Brazil
- Coutinho, Luiz Alberto soares de araújo, UFPE, Recife, Brazil
- Vaz, Julia Braga, UFPE, Recife, Brazil
Background
Bone turnover (BT) markers reflect bone cell activity and are useful in the diagnosis and management of chronic kidney disease-mineral and bone disorders. Bone biopsy (BB) is considered gold standard for diagnosing renal osteodystrophy, although it should be reserved just for certain patients. The objective of this study was to evaluate the predictive value of intact parathyroid hormone (iPTH) and total alkaline phosphatase (tALP) as BT markers.
Methods
This was a cross-sectional retrospective diagnostic test study. Two hundred and eleven patients were assessed through BB and serum levels of iPTH and tALP. iPTH assays were performed using the same methodology (chemiluminescence: NR: 15-65 pg/mL). For the tALP analysis, an index representing the ratio between tALP and the maximum reference value for the method was used, since there are tests with different methodologies. According to histological diagnosis, the patients were divided into high turnover (HT), those with fibrous osteitis and mixed disease, and low turnover (LT), those with adynamic bone disease and osteomalacia. An analysis was conducted in order to derive the area under the receiver operating characteristic (ROC) curve (AUROC) to determine the diagnostic ability of BT as a biomarker.
Results
Patients (48.9 years) had been on hemodialysis for 9.5 years, of whom 84% and 16% were classified as HT and LT, respectively. The median serum level of iPTH was 1296 in the HT patients, and 116 in LT patients. The median tALP index was 1.82 for the HT and 0.9 for the LT patients. To predict HT, the iPTH presented an AUROC of 0.908, with a cutoff value of 363 with a sensitivity of 82.5% and a specificity of 88%; while the tALP index demonstrated an AUROC of 0.747, with a cutoff value of 1.01, with a sensitivity of 72.3% and a specificity of 65%. To predict LT, the iPTH and tALP index were not good markers, with an AUROC of 0.092 and 0.253, respectively. Limitations: Histomorphometry and bone alkaline phosphatase were not performed; Predominance of severe secondary hyperparathyroidism.
Conclusion
Our results have demonstrated that the iPTH and tALP were excellent predictors for HT, but it was evident that iPTH was far superior.