Original Paper Nephron Clin Pract 2013;124:124–131 DOI: 10.1159/000355860
Received: April 15, 2013 Accepted: September 17, 2013 Published online: November 2, 2013
Maintaining Normal Levels of Ionized Calcium during Citrate-Based Renal Replacement Therapy Is Associated with Stable Parathyroid Hormone Levels Mário Raimundo a, c Siobhan Crichton b Katie Lei a Barnaby Sanderson a John Smith a John Brooks a Josephine Ng a Joanna Lemmich Smith a Catherine McKenzie a Richard Beale a Helen Dickie a Marlies Ostermann a a
Department of Critical Care, Guy’s and St Thomas’ Foundation Hospital, King’s Health Partners and Division of Health and Social Care Research, King’s College London, London, UK; c Hospital de Santa Maria, Centro Hospitalar Lisboa Norte, Lisbon, Portugal b
Abstract Background/Aims: 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 citratebased CRRT with physiologic target systemic [Cai] 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 [Cai] 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
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p = 0.49, respectively). In a mixed-effects model, each 0.1 mmol/l increase in serum [Cai] 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 [Cai] within the physiologic range was associated with stable PTHi levels. © 2013 S. Karger AG, Basel
Introduction
Citrate-based regional anticoagulation is an effective and safe alternative to heparin to keep the circuit patent during continuous renal replacement therapy (CRRT) [1–9]. The recently published Acute Kidney Injury Guideline by the Kidney Disease Improving Global Outcomes Group recommended using regional citrate anticoagulation as the first-line therapy for patients on CRRT [10]. The method is based on pre-filter administration of citrate which lowers ionized calcium (Cai)
