title: Association between very low PTH levels and poor survival rates in haemodialysis patients: results from the French ARNOS cohort.
abstract: BACKGROUND
  A very low parathyroid hormone (PTH) level (VLPL) is associated with an increased risk of adynamic bone disease, vascular calcification, and mortality in haemodialysis (HD) patients. The aim of the study was to assess the frequency, the associated factors, and the prognosis of non-surgical VLPL in a cohort of prevalent HD patients.
  
  
  METHODS
  In July 2005, a cross-sectional study was performed on the French ARNOS cohort in 1,348 prevalent HD patients from 24 dialysis centres in the Rhône-Alpes area. Patients with a baseline intact PTH level <50 pg/ml (VLPL, Group 1) and ≥ 50 pg/ml (Group 2) were compared and a 42-month survival analysis was performed. Patients with prevalent or incident parathyroidectomy were excluded.
  
  
  RESULTS
  We studied 1,138 prevalent HD patients. As compared to patients of Group 2 (n = 1,019), patients with VLPL (Group 1, n = 119) had lower serum albumin levels (34.5 ± 5 vs. 36.4 ± 5 g/l, p < 0.0001), less protein intake (nPCR 0.99 ± 0.28 vs. 1.1 ± 0.28 g/kg/day, p = 0.01), higher calcaemia (2.30 ± 0.2 vs. 2.26 ± 0.2 mmol/l, p = 0.01) and were more frequently treated with calcium carbonate (67 vs. 54%, p < 0.001). Patients with VLPL had a higher mortality rate (HR: 1.4 (1.07-1.8), p = 0.006) after adjustment for age, gender, diabetes, and dialysis vintage. The odds ratios of mortality for patients with VLPL remained higher in all calcaemia and serum albumin quartiles. Only 3/119 patients in Group 1 did not receive any PTH-lowering therapies (i.e. calcium carbonate (67%), alfacalcidol (38%), cinacalcet (10.1%), and dialysate calcium ≥ 1.5 mmol/l (94%)).
  
  
  CONCLUSIONS
  In this observational French cohort, VLPL was observed in 10% of prevalent HD patients and was associated with poor survival rates. An inadequate therapeutic strategy could be responsible for this observation. The real consequences of this iatrogenic adynamic bone disease remain hypothetical, but it may be related to the risk of developing vascular calcification. It is hypothesized that a more adequate strategy, using fewer PTH-lowering therapies in cases of VLPL, may help in improving the poor prognosis.
authors.affiliation: Centre de Rein Artificiel, Service d'Hémodialyse, Tassin la Demi-Lune, France. guillaume-jean-crat@wanadoo.fr
authors.forename: G
authors.initials: G
authors.lastname: Jean
authors.forename: D
authors.initials: D
authors.lastname: Lataillade
authors.forename: L
authors.initials: L
authors.lastname: Genet
authors.forename: E
authors.initials: E
authors.lastname: Legrand
authors.forename: F
authors.initials: F
authors.lastname: Kuentz
authors.forename: X
authors.initials: X
authors.lastname: Moreau-Gaudry
authors.forename: D
authors.initials: D
authors.lastname: Fouque
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D001851:Bone Diseases, Metabolic / Q000097:blood / Q000209:etiology / Q000401:mortality; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D005602:France / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood*; D006435:Renal Dialysis / Q000009:adverse effects / Q000401:mortality*; D015996:Survival Rate / Q000639:trends
chemical_list: D015415:Biomarkers; D010281:Parathyroid Hormone