Large Academic Hospital Laboratory Investigates a Major Pre-Analytical Challenge in Africa and Developing Countries

Background: Delay in serum separation from red blood cells in samples collected from most primary healthcare facilities and transported to a laboratory for analysis is of great concern. Standard guidelines state that serum or plasma should be separated from cells within 2 hours of collection. The aim was to determine effects of delayed sample separation on measured biochemical analytes. The objective was to store blood samples in primary collection tubes at 20-25°C post venesection, then separate, and analyse samples of selected analytes. Methods: Multiple sample tubes of whole blood were collected from one of the authors volunteer, and subjected to time delays in centrifugation. The baseline serum was separated from red blood cells within 30 minutes of post venesection to allow adequate coagulation. Twenty analytes were studied using 2 analytical platforms. Percentage variation and standard error method were used to evaluate time-dependent variability in analytes. Total change limit was used to measure significant changes within-run variability for both platforms. Results: Most analytes were stable up to day 3 to 4 on both platforms. Serum CO2, CL, Ca, ALT and ALB were stable up to 8 days when they were measured on Cobas 8000®. BUN, TRIG, TB, CHOL, AST, ALT and ALB were stable up to 10 days on Dimension® CCS. K showed significant changes at 2h on both platforms at initial measurements. It was out-of-range at day 10 on Dimension® CCS. Serum creatinine levels showed substantial changes at day 2 on Dimension® analyzer and on Cobas 8000® at day 3. Conclusions: The study showed stability of wide range of serum analytes at 20-25°C for several days. The acceptable results can be achieved if samples are centrifuged the same day and analyzed later for most of biochemical analytes.