The effect of time, temperature and P-chloro-mercuriphenylsulfonic acid during serum storage on HDLᵼ-C and HDL₃-C concentration

Background: Accurate measurement of clinical laboratory parameters plays an essential role in the correct interpretation of clinical biochemistry abnormalities. The purpose of this study was evaluation the time and temperature effect on HDLᵼ-C, HDL₂-C and HDL₃-C stability during storage. Material and Methods: 50 adult healthy subjects were participated. For the isolation of HDLᵼ-C, we used precipitation method and HDLᵼ-C data was analyzed by the Abell-Kendal cholesterol reference method. The remaining serum were dispensed into 12 sample tubes and divided into two groups. One of each group was stored upright at room temperature (approximately 25 oC) while another at 4 oC and the half of each group tubes were received p-chloro - mercuriphenylsulfonic acid  (PCMPS). The stored serum aliquots from all temperature and time points were analyzed on 1, 2, 3 days post collection. Results: HDLᵼ-C concentration at the temperature of room in 24 hours is not changed significantly but over the time decreased (7.2% in 3 days). In addition of PCMPS inhibitor, the concentration is increased  by 17.3% in 3 days. But in 4oC, with or without PCMPS, there is no a significant change in the HDLᵼ-C concentration. HDL₃-C was found to be the most stable lipoprotein studied because of non-significant effect of storage time and temperature on it. Conclusion: The results suggest 4oC as the ideal storage condition for the preservation of human serum samples for HDLᵼ-C assay. Also it is suggested that HDL concentration estimation should be performed in the first 24 hours of samples collection. PCMPS addition didn’t affect HDL subtypes concentration in 4oC.