title: Maintaining normal levels of ionized calcium during citrate-based renal replacement therapy is associated with stable parathyroid hormone levels.
abstract: OBJECTIVE
  Citrate is an effective anticoagulant during continuous renal replacement therapy (CRRT). Previous studies showed raised parathyroid hormone (PTH) levels when aiming for serum ionized calcium [Cai] between 0.8 and 1.1 mmol/l. Our objective was to assess whether citrate-based CRRT with physiologic target systemic [Ca(i)] between 1.12 and 1.20 mmol/l could maintain stable PTH levels.
  
  
  METHODS
  Measurement of intact PTH (PTHi) in 30 consecutive critically ill patients treated with citrate-based CRRT.
  
  
  RESULTS
  Thirty patients [mean age: 70.4 (SD 11.3) years; 56.7% males] were enrolled. Mean serum [Ca(i)] was 1.16 mmol/l (SD 0.09), 1.13 mmol/l (SD 0.09), 1.17 mmol/l (SD 0.05) and 1.16 mmol/l (SD 0.04) at baseline, 12, 24 and 48 h, respectively (p = 0.29). Median PTHi levels (interquartile range) at baseline, 12, 24 and 48 h were 66.5 (43-111), 109 (59.5-151.5), 88.5 (47-133) and 85 pg/ml (53-140), respectively. The differences between baseline and 12 h and across all time points were statistically not significant (p = 0.16 and p = 0.49, respectively). In a mixed-effects model, each 0.1 mmol/l increase in serum [Ca(i)] was associated with a 31.2% decrease in PTHi (p < 0.001). Results were unchanged after adjustment for age, gender, magnesium, phosphate, arterial pH and time spent on CRRT.
  
  
  CONCLUSIONS
  Maintaining systemic [Ca(i)] within the physiologic range was associated with stable PTHi levels.
authors.affiliation: Department of Critical Care, Guy's and St Thomas' Foundation Hospital, King's Health Partners, King's College London, London, UK.
authors.forename: Mário
authors.initials: M
authors.lastname: Raimundo
authors.forename: Siobhan
authors.initials: S
authors.lastname: Crichton
authors.forename: Katie
authors.initials: K
authors.lastname: Lei
authors.forename: Barnaby
authors.initials: B
authors.lastname: Sanderson
authors.forename: John
authors.initials: J
authors.lastname: Smith
authors.forename: John
authors.initials: J
authors.lastname: Brooks
authors.forename: Josephine
authors.initials: J
authors.lastname: Ng
authors.forename: Joanna
authors.initials: J
authors.lastname: Lemmich Smith
authors.forename: Catherine
authors.initials: C
authors.lastname: McKenzie
authors.forename: Richard
authors.initials: R
authors.lastname: Beale
authors.forename: Helen
authors.initials: H
authors.lastname: Dickie
authors.forename: Marlies
authors.initials: M
authors.lastname: Ostermann
mesh_terms: D000368:Aged; D000925:Anticoagulants / Q000627:therapeutic use; D002118:Calcium / Q000097:blood*; D019343:Citric Acid / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D007477:Ions; D007676:Kidney Failure, Chronic / Q000378:metabolism / Q000628:therapy; D008297:Male; D010281:Parathyroid Hormone / Q000097:blood*; D017582:Renal Replacement Therapy / Q000009:adverse effects* / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013927:Thrombosis / Q000209:etiology* / Q000517:prevention & control*; D016896:Treatment Outcome
chemical_list: D000925:Anticoagulants; D007477:Ions; D010281:Parathyroid Hormone; D019343:Citric Acid; D002118:Calcium