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Background: To study calcium homeostasis during citrate-based compared to nadroparin-based CVVH in critically-ill patients with acute renal failure., Methods: 11 patients were observed during citrate anticoagulation, 9 with nadroparin and 10 controls. Citrate was chosen for patients with active or at risk for bleeding., Results: The controls had, at 24 h, a median serum iCa of 1.1 mmol/l, the citrate group 0.87 mmol/l and the nadroparin group 1.1 mmol/l (citrate vs. control p = 0.001, citrate vs. nadroparin p = 0.002). At 48 h, iCa was not significantly different anymore. Ca balance was negative for the citrate group in contrast to the nadroparin group (p = 0.012). Median serum PTH was higher (30.0 pmol/l vs. 6.5 pmol/l, p = 0.003) in the citrate group., Conclusion: With a relative low target-serum-iCa (0.8-0.9 mmol/l) citrate CVVH-treated patients had a negative daily calcium balance and a temporarily lower iCa level resulting in an enhanced PTH response in comparison to nadroparin., (Copyright 2007 S. Karger AG, Basel.)

Background: The objective of this study was to elucidate the most practical and effective laboratory measurement for monitoring citrate in critically ill patients undergoing citrate-anticoagulated continuous venovenous haemofiltration (CVVH)., Methods: This observational study was performed at the mixed medical and surgical intensive care unit of a regional teaching hospital. The study population comprised ten consecutive critically ill patients with acute renal failure and indication for haemofiltration with the use of regional anticoagulation with citrate. Serum samples for the measurement of citrate and total and ionised calcium were taken from the pre- and post-filter compartments and from the arterial circulation of patients during citrate-anticoagulated CVVH., Results: Receiver operating characteristic (ROC) curve analysis showed that for detecting citrate overdose (defined as a citrate concentration >1.0 mmol/L) the best cut-off limits for total/ionised calcium and ionised calcium were 2.1 and 0.8 mmol/L, respectively. Sensitivity and specificity for the cut-off limit of 2.1 for total/ionised calcium were 89% and 100%, and 84% and 100%, respectively, for the cut-off limit of 0.8 mmol/L for ionised calcium., Conclusions: In patients without liver insufficiency, total/ionised calcium performed slightly better than ionised calcium in detecting elevated citrate concentrations. However, because of the simplicity of its measurement, ionised calcium is preferred. Measurement of citrate is not necessary.

Background: Measurement of lactate dehydrogenase (LDH) with the International Federation of Clinical Chemistry (IFCC)-recommended method in plasma was reported unreliable with primary evacuated lithium-heparin tubes from Becton-Dickinson, despite adequate removal of platelets from the plasma by optimized sample preparation. In this study, the composition of the top layer of the heparin plasma was investigated in relation to these duplicate errors. Method: Microscopic evaluation of cytospin preparations of the top layer of the plasma was compared with the difference between duplicates in the IFCC-recommended LDH assay using a Hitachi 911 analyser. Results: Duplicate errors could not be explained by the presence of one of the individual cell types. In 16 samples with cellular aggregates absent, three did show duplicate errors; all three had a moderate amount of red blood cells present. Conclusion: The presence of cellular aggregates in the top layer of the plasma was the main determinant for the occurrence of the high frequency of duplicate errors in the IFCC-recommended LDH method. [ABSTRACT FROM AUTHOR]