Stability of serum total cholesterol, triglycerides, and plasma glucose of healthy individuals at different storage conditions

Abstract

Evaluation of the stability of serum and plasma analytes under different temperatures and time points is vital since it significantly affects the pre-analytical errors. The aim of the study was to determine the stability of serum total cholesterol and triglyceride and plasma glucose of healthy individuals under different storage conditions (25-30°C and 2-8°C) and at different time points (1-hour, 4-hour, 6-hour, and 24-hour). Venous blood samples were collected from healthy individuals aged between 20-50 years after a 12-hour fast. Plasma and serum were separated and stored at different temperatures (25-30°C and 2-8°C) and different time points (1-hour, 4-hour, 6-hour, and 24-hour). Results indicated a significant difference between the mean plasma glucose concentration at room temperature (25-30°C) and refrigerated temperature (2-8°C) at 1-hour (0.072%, p = 0.05). However, there were no significant differences in mean serum total cholesterol concentrations (p = 0.633) and mean serum triglyceride concentrations (p = 0.246) between these temperatures at 1-hour time point. Regarding time points (1-hour, 4-hour, 6-hour, and 24-hour), significant differences in plasma glucose concentrations occurred at 24-hour (10.03%, p = 0.001) at room temperature (25-30°C) and 6-hour (8.79%, p = 0.003) at refrigerated temperature (2-8°C) compared to the 1-hour reference values. Additionally, there were significant differences in serum total cholesterol concentration at 4-hour (12.55%, p = 0.000) and serum triglyceride at 24-hour (29.18%, p = 0.001) compared to the reference values obtained at 1-hour at room temperature (25-30°C). No significant differences were observed among the time points (1-hour, 4-hour, 6-hour, and 24-hour) for serum total cholesterol (p = 0.507) and serum triglyceride values (p = 0.761) at refrigerated temperature (2-8°C). Plasma glucose is unstable at both room temperature (25-30°C) and refrigeration (2-8°C), with recommended testing within 6 hours at room temperature (25-30°C) and stored in a refrigerator (2-8°C) if delayed. It is better to estimate serum total cholesterol within 1-hour of collection at room temperature (25-30°C) while serum triglyceride concentration within 6 hours at the same temperature to obtain accurate and reliable results.