Q: What is the significance of "calcium ratio" during Continuous Renal Replacement Therapy (CRRT)?


Answer: If the ratio of total serum calcium to ionized calcium concentration exceeds 2.5, when both total and ionized calcium are measured in mmol/l or exceeds more than 10 if total calcium is measured in mg/dl., is a strong indicator of citrate toxicity. Treatment is the discontinuation of Citrate.



Reference: 

 Meier-Kriesche HU, Gitomer J, Finkel K, DuBose T. Increased total to ionized calcium ratio during continuous venovenous hemodialysis with regional citrate anticoagulation. Crit Care Med 2001; 29:748. 

Bakker AJ, Boerma EC, Keidel H, et al. Detection of citrate overdose in critically ill patients on citrate-anticoagulated venovenous haemofiltration: use of ionised and total/ionised calcium. Clin Chem Lab Med 2006; 44:962.