Bone Histomorphometry and 18F-Sodium Fluoride Positron Emission Tomography Imaging: Comparison Between only Bone Turnover-based and Unified TMV-based Classification of Renal Osteodystrophy

Louise Aaltonen,Kaj Metsärinne,Inari S Burton,Marko Seppänen,Eliisa Löyttyniemi,Heikki Kröger,Niina Koivuviita

doi:10.1007/s00223-021-00874-9

Abstract

Bone biopsy is the gold standard for characterization of renal osteodystrophy (ROD). However, the classification of the subtypes of ROD based on histomorphometric parameters is not unambiguous and the range of normal values for turnover differ in different publications. 18F-Sodium Fluoride positron emission tomography (18F-NaF PET) is a dynamic imaging technique that measures turnover. 18F-NaF PET has previously been shown to correlate with histomorphometric parameters. In this cross-sectional study, 26 patients on dialysis underwent a 18F-NaF PET and a bone biopsy. Bone turnover-based classification was assessed using Malluche’s historical reference values for normal bone turnover. In unified turnover-mineralization-volume (TMV)-based classification, the whole histopathological picture was evaluated and the range for normal turnover was set accordingly. Fluoride activity was measured in the lumbar spine (L1–L4) and at the anterior iliac crest. On the basis of turnover-based classification of ROD, 12% had high turnover and 61% had low turnover bone disease. On the basis of unified TMV-based classification of ROD, 42% had high turnover/hyperparathyroid bone disease and 23% had low turnover/adynamic bone disease. When using unified TMV-based classification of ROD, 18F-NaF PET had an AUC of 0.86 to discriminate hyperparathyroid bone disease from other types of ROD and an AUC of 0.87, for discriminating adynamic bone disease. There was a disproportion between turnover-based classification and unified TMV-based classification. More research is needed to establish normal range of bone turnover in patients with CKD and to establish the role of PET imaging in ROD.

Highlights

As chronic kidney disease (CKD) progresses, a majority of the patients have abnormalities in mineral homeostasis referred to as renal osteodystrophy (ROD) [1,2,3,4]
Two patients with low turnover had a clear mineralization defect based on the bone biopsy
The unified TMV-based classification of ROD is statistically associated with turnover-based classification (p < 0.001)

Summary

Introduction

As chronic kidney disease (CKD) progresses, a majority of the patients have abnormalities in mineral homeostasis referred to as renal osteodystrophy (ROD) [1,2,3,4]. Abnormalities are seen in bone turnover, mineralization and volume. Hyperparathyroid bone disease is defined as high turnover, with elevated osteoblast and osteoclast activities, increased osteoid width, and peritrabecular fibrosis. Adynamic bone disease is defined as low turnover with reduced osteoblast and osteoclast activities. Bone biopsy with the following histomorphometric analysis is the gold standard for evaluation of ROD [1, 5, 6]. Bone histomorphometric parameters can be divided into structural and remodeling [7, 8]. Structural parameters measure bone mass and structure.

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Conclusion