title: Determinants of bone mineral density in patients on haemodialysis or peritoneal dialysis--a cross-sectional, longitudinal study.
abstract: BACKGROUND
  The aim of the study was to identify biomarkers of alteration in bone mineral density (BMD) in patients on haemodialysis (HD) and peritoneal dialysis (PD).
  
  
  METHODS
  In a cross-sectional, longitudinal study dual-energy X-ray absorptiometry scans were performed in 146 HD-patients and 28 PD-patients. Follow-up after 14 months (mean) was conducted in 73 patients. As potential biomarkers we investigated parathyroid hormone (PTH), 25-hydroxy vitamin-D, ionised calcium, albumin, phosphate, and total alkaline phosphatases (t-ALP).
  
  
  RESULTS
  Both groups of dialysis patients had lower BMD in the femoral neck (BMD(neck)) (P < 0.001) and forearm (BMD(forearm)) (P < 0.001) compared to healthy controls, but comparable BMD in the lumbar spine (BMD(spine)). BMD did not differ between dialysis types, but patients ever-treated with glucocorticoids had significantly lower BMD, while patients with polycystic kidney disease had higher BMD. BMD correlated with body weight, actual age, age at initiation of dialysis, duration of dialysis and levels of PTH and t-ALP. However, t-ALP only remained associated with low BMD(spine) after adjusting for other factors (P = 0.001). In the follow-up study all patients had decreased BMD in all three locations, but only for the lumbar spine there was a significant association between BMD and the bone markers t-ALP (P = 0.009) and PTH (P = 0.013).
  
  
  CONCLUSIONS
  Both HD and PD patients have low BMD, and increased concentrations of t-ALP is associated BMD(spine) after adjustment, while PTH and t-ALP is associated with decrease in BMD(spine) over time. This substantiates the use of these biomarkers in both types of dialysis patients.
authors.affiliation: Department of Clinical Biochemistry and Pharmacology, Odense University Hospital, Denmark. mads.nybo@rsyd.dk
authors.forename: Mads
authors.initials: M
authors.lastname: Nybo
authors.forename: Bente
authors.initials: B
authors.lastname: Jespersen
authors.forename: Michael
authors.initials: M
authors.lastname: Aarup
authors.forename: Charlotte
authors.initials: C
authors.lastname: Ejersted
authors.forename: Anne Pernille
authors.initials: AP
authors.lastname: Hermann
authors.forename: Kim
authors.initials: K
authors.lastname: Brixen
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density / Q000502:physiology*; D003430:Cross-Sectional Studies; D005260:Female; D050723:Fractures, Bone / Q000453:epidemiology / Q000209:etiology* / Q000378:metabolism; D006801:Humans; D007676:Kidney Failure, Chronic / Q000150:complications / Q000453:epidemiology / Q000628:therapy*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D010530:Peritoneal Dialysis / Q000009:adverse effects / Q000706:statistics & numerical data*; D006435:Renal Dialysis / Q000009:adverse effects / Q000706:statistics & numerical data*; D012307:Risk Factors; D055815:Young Adult