Study: Pseudohypernatremia from Trisodium Citrate Locking Solution

Considered the access of last resort for nearly all patients, central venous catheters (CVCs) pose a potential risk for infection and patency-related complications. For patients who have a CVC, trisodium citrate (TSC) used as a locking solution has shown promise as a substitute for unfractionated heparin for helping prevent CVC dysfunction. However, pseudohypernatremia may occur when 30% TSC is used. An analysis was conducted by DaVita EMEA to identify pre-dialysis sodium levels and the prevalence of hypernatremia in patients who were given TSC as a locking solution versus patients given unfractionated heparin.

In the analysis, patients with CVCs that were locked with 30% TSC had significantly higher pre-dialysis sodium serum concentrations than those with CVCs that were locked with unfractionated heparin. The concentrations were also higher than those of patients who had either an arteriovenous fistula or an arteriovenous graft. It is likely that TSC contamination of the blood samples drawn from CVCs led to the observed high sodium concentrations. Follow-up analysis of serum sodium in blood samples drawn from peripheral veins showed no evidence of hypernatremia.

A high sodium concentration can lead to significant diagnostic laboratory investigations. To help avoid unnecessary investigations, it is critical to adhere to recommended procedures for collecting blood samples from a CVC—discarding a proper volume first before collecting the sample to help avoid TSC contamination of the sample.

For more information, read the research poster (which was presented at ASN), here.