SODIUM CITRATE 3.2% AND 3.8%
The assumption is that you have collected a quality sample following proper handling
conditions1. Sodium citrate concentrations can have significant affect on APTT and PT assay results, especially when result are outside of the normal range and responsive reagents are used. Laboratories should determine their normal range of APTT and PT based on one citrate concentration, and must consistently use this concentration for all patient samples until a new normal range is developed. NCCLS recommends the use of 3.2% citrate concentration.
Potential issues between 3.2% and 3.8% sodium citrate concentration are as follows:
- When responsive reagents are used, statistical differences in APTT and PT test results between
the two citrate concentration will occur.
- The PT test is consistently higher when responsive reagent and 3.8% sodium citrate are used.
- Normal ranges for APTT and PT may shift higher when 3.8% citrate is compared to 3.2% citrate with responsive reagents. Less variation in the normal range occurs between the citrate
concentrations when non responsive reagents (ex. Dude®Actin®, Thromboplastin C.Plus) are used.
- When non responsive reagents are used, varying the citrate concentration had little clinical significance except with patients receiving IV heparin Therapy.