title: The pitfall of treating low bone turnover: Effects on cortical porosity.
abstract: Although it is recognized that cortical bone contributes significantly to the mechanical strength of the skeleton, little is known about this compartment from bone biopsy studies, particularly in CKD patients. In addition, there is no prospective data on the effects of CKD-MBD therapy on cortical porosity (Ct.Po). This is a post hoc analysis on data from a randomized controlled trial on the effects of different phosphate binders on bone remodelling. Therapy was adjusted according to the first biopsy, and included sevelamer or calcium acetate, calcitriol and changes in calcium dialysate concentration. We measured Ct.Po at baseline and one year after. Fifty-two patients (46±13years old, 67% women and 60% white) were enrolled. Ct.Po was already high at baseline in 85% of patients [30% (17, 46)] and correlated with PTH (p=0.001). Low bone turnover was seen in 28 patients (54.9%). After one-year treatment, PTH increased in patients with low turnover, as intended. However, increased Ct.Po was seen in 49 patients (94%). This increase correlated with the delta of phosphate (p=0.015) and the delta of PTH (p=0.03); it was also higher among non-white patients than in white patients (p=0.039). The risk of increase in Ct.Po was 4.5 higher among non-white patients. Adjusted multiple regression analysis showed that the delta of Ct.Po was dependent on delta PTH and race (r(2)=0.193). We concluded that in an attempt to increase bone turnover, the increase in PTH levels might be associated with higher cortical porosity, particularly in non-white patients. Whether this finding leads to a high risk of fracture deserves further investigation.
authors.affiliation: Nephrology Division, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Maria Julia C L N
authors.initials: MJ
authors.lastname: Araujo
authors.affiliation: Nephrology Division, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Cristina
authors.initials: C
authors.lastname: Karohl
authors.affiliation: Nephrology Division, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Rosilene M
authors.initials: RM
authors.lastname: Elias
authors.affiliation: Nephrology Division, Pontifícia Universidade Católica do Paraná, Curitiba, Brazil; Nephrology Division, Universidade Federal do Paraná, Curitiba, Brazil.
authors.forename: Fellype C
authors.initials: FC
authors.lastname: Barreto
authors.affiliation: Nephrology Division, Pontifícia Universidade Católica do Paraná, Curitiba, Brazil.
authors.forename: Daniela Veit
authors.initials: DV
authors.lastname: Barreto
authors.affiliation: Nephrology Division, Universidade Federal de São Paulo, São Paulo, Brazil.
authors.forename: Maria Eugenia F
authors.initials: ME
authors.lastname: Canziani
authors.affiliation: Nephrology Division, Universidade Federal de São Paulo, São Paulo, Brazil.
authors.forename: Aluizio B
authors.initials: AB
authors.lastname: Carvalho
authors.affiliation: Nephrology Division, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Vanda
authors.initials: V
authors.lastname: Jorgetti
authors.affiliation: Nephrology Division, Universidade de São Paulo, São Paulo, Brazil; Medicine Master Degree Program, Universidade Nove de Julho, UNINOVE, São Paulo, Brazil. Electronic address: rosa.moyses@uol.com.br.
authors.forename: Rosa M A
authors.initials: RM
authors.lastname: Moyses
mesh_terms: D001706:Biopsy; D016723:Bone Remodeling / Q000502:physiology*; D000071538:Cortical Bone / Q000473:pathology / Q000503:physiopathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D016062:Porosity
keywords: Bone biopsy; Cortical bone; Hemodialysis; Mineral metabolism; Parathyroid hormone