Impact of serum-clot contact time on lactate dehydrogenase and inorganic phosphorus serum levels

OBJECTIVES: The aim of this study is to determine the longest acceptable serum-clot contact time before centrifugation in lactate dehydrogenase and inorganic phosphorus analysis. MATERIALS AND METHODS: The LDH and inorganic phosphorus serum levels from 103 adults were analyzed at three different storage times. The three measures were done immediately (T0), after a 2-h serum-clot contact (T2) and after a 4-h serum-clot contact (T4). A paired two-tailed Student t-test evaluated the impact of the serum-clot contact time on the serum levels. Another approach using analytical reproducibly and intra-individual variability was used. Furthermore, we have compared the mean percentage deviation to the measurement uncertainty. RESULTS: The LDH serum level is not significantly impacted by the three different studied serum-clot contact times. The immediate Phosphorus serum level is not significantly different from the 2-h serum-clot contact condition. However, after a 4-h serum-clot contact, the phosphorus serum level is significantly lower than the immediate phosphorus serum level. Considering the reference change value approach, an acceptable mean variation was shown for inorganic phosphorus serum level after a 4-h serum-clot contact time. After a 4-h serum-clot contact, LDH and phosphorus mean percentage deviation are below our measurement uncertainties. CONCLUSION: This study evidences that in our daily practices a 4-h serum-clot contact time for LDH and inorganic phosphorus analysis is acceptable.