title: Variant of adynamic bone disease in hemodialysis patients: fact or fiction?
abstract: BACKGROUND
  Adynamic bone disease is a type of renal osteodystrophy characterized by low bone turnover and paucity of bone cells. It was proposed that a new type of this disease featuring high osteoclastic resorption without parathyroid hormone stimulus and designated adynamic bone disease variant occurs in hemodialysis patients. The present study is designed to evaluate the frequency and characteristics of both diseases in a large series of bone biopsy specimens.
  
  
  METHODS
  We reviewed 1,160 bone biopsy specimens from hemodialysis patients. Specimens in which adynamic bone disease was diagnosed were selected and categorized as classic or variant based on osteoclastic surface.
  
  
  RESULTS
  In 218 bone biopsy specimens (18.8%), adynamic bone disease was identified, whereas the variant form was identified in 35 specimens (38.8%). Biopsy specimens categorized as the variant form were from patients who were younger and had greater phosphorus and parathyroid hormone levels. Histologically, the variant form presented greater osteoid volume, fibrosis volume, osteoid surface, osteoblast surface, and eroded surface. Similarly, values for all dynamic parameters were greater in the variant group. Osteoclastic surface correlated with phosphorus level, parathyroid hormone level, and osteoblast surface. Age and osteoblast surface were identified as independent determinants of the variant form.
  
  
  CONCLUSIONS
  Adynamic bone disease variant seems to occur in younger hemodialysis patients with greater levels of parathyroid hormone, which acts on cell-covered bone surfaces. It probably is a transitional phase from low- to high-turnover status, rather than a true entity within the spectrum of renal osteodystrophy.
authors.affiliation: Nephrology Department, Federal University of São Paulo School of Medicine, Brazil. lillianrocha@yahoo.com.br
authors.forename: Lillian A
authors.initials: LA
authors.lastname: Rocha
authors.forename: Andrea
authors.initials: A
authors.lastname: Higa
authors.forename: Fellype C
authors.initials: FC
authors.lastname: Barreto
authors.forename: Luciene M
authors.initials: LM
authors.lastname: dos Reis
authors.forename: Vanda
authors.initials: V
authors.lastname: Jorgetti
authors.forename: Sérgio A
authors.initials: SA
authors.lastname: Draibe
authors.forename: Aluizio B
authors.initials: AB
authors.lastname: Carvalho
mesh_terms: D000328:Adult; D017668:Age of Onset; D001706:Biopsy; D001842:Bone and Bones / Q000473:pathology; D012080:Chronic Kidney Disease-Mineral and Bone Disorder / Q000209:etiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood / Q000502:physiology; D006435:Renal Dialysis / Q000009:adverse effects*; D012189:Retrospective Studies
chemical_list: D010281:Parathyroid Hormone