Table 1.
Biochemical parameters from pre-dialysis CKD and from dialysis patients.
Table 2.
Bone histomorphometry, PTHR1 expression, and canopy coverage in bone specimens from pre-dialysis CKD and from dialysis patients.
Fig 1.
Light microscopic features of canopies in patients treated with maintenance dialysis.
Toluidine blue staining of a 5 μm undecalcified section of iliac crest trabecular bone from patients treated with maintenance dialysis demonstrating osteoid surfaces (OS) colonized by osteoblasts (A-B) and eroded surfaces (ES) colonized by osteoclasts (OC) and reversal cells (C-D), which are separated from the bone marrow by either a thin (A, C) or thick (B, D) canopy. The thin canopies are marked with cyan arrowheads and diamonds, while the thick canopies are framed by two cyan dotted lines.
Fig 2.
Immunostaining for PTHR1 and RANKL in trabecular bone from a patient treated with maintenance dialysis.
A-C: PTHR1 immunoreactivity (red) was observed in both thin and thick canopies above eroded surface (ES) and osteoid surface (OS). On the eroded surface the reversal cells, but not the osteoclasts (OC), demonstrated PTHR1 immunoreactivity (A). No osteoblasts on the osteoid surface showed PTHR1 immunoreactivity (B-C). D-F: RANKL immunoreactivity was also observed in both thin and thick canopies above eroded and osteoid surfaces. Only the reversal cells and not the osteoclasts on the eroded surface demonstrated RANKL immunoreactivity (D). No osteoblasts on the osteoid surface demonstrated RANKL immunoreactivity (E-F). Thin canopies are marked with green arrowheads and diamonds while the thick canopies are framed by two green dotted lines.
Fig 3.
Co-localization of PTHR1 and RANKL in trabecular bone of a dialysis patient.
Immunolocalization of PTHR1 (green), RANKL (red), and their co-localization (yellow) in trabecular bone of a patient treated with maintenance dialysis. Thin canopies are marked with white arrowheads and diamonds while thick canopies are framed by two white dotted lines. Note that PTHR1 and RANKL co-localize in canopies.
Fig 4.
PTH levels as a function of the number of surfaces with canopy coverage in patients with renal osteodystrophy.
Lines represent median values; bars represent interquartile ranges.
Fig 5.
PTH levels (A) and the number of surfaces with canopy coverage (B) as a function of ROD diagnosis in dialysis patients.
Lines represent median values; bars represent interquartile ranges. Low: lone bone turnover; normal: normal bone turnover; mild: mildly increased bone turnover; 2°HPT: severe high bone turnover/secondary hyperparathyroidism; mixed: mixed uremic osteodystrophy.
Table 3.
Relationships between biochemical/bone histormorphometric variables and the number of surfaces with canopy coverage or PTHR1 immunoreactivity.
Table 4.
Multiple linear regression model considering the contributions of PTH levels, and extent of osteoid and osteoclast surfaces in the prediction of the canopy coverage.
Fig 6.
Bone histomorphometric parameters of bone formation and resorption as a function of canopy coverage observed by histology.
A) osteoid surfaces/bone surface (OS/BS); B) eroded surface/bone surface (ES/BS). C) osteoclast surface/bone surface (Oc.S/BS); D) reversal surface/bone surface (Rv.S/BS). Lines represent median values; bars represent interquartile ranges.
Fig 7.
Histologic features of fibrosis and canopies.
A) Histologic section demonstrating areas of bone formation (osteoid surface; OS) and resorption (eroded surface; ES). B) Higher magnification of area of bone formation demonstrating organized, layered appearance of canopy overlying bone forming osteoblasts (OB). C) Disorganization characteristic of fibrosis overlying bone-resorbing osteoclasts (OC).