engleski

Preanalytical stability of clinically relevant chemistry analytes in serous fluids

BACKGROUND-AIM: Preanalytical stability for analytes in serous fluids (SF) is largely unknown. Our aim was to evaluate stability of clinically relevant analytes in SF (i.e. pleural and peritoneal effusions) stored under different conditions prior to analysis. METHODS: Leftovers from 20 consecutive SF samples initially referred to our laboratory for routine analysis were separated. Baseline values for total proteins (TP), albumin (ALB), lactate dehydrogenase (LD), cholesterol (CHOL), triglycerides (TRIG), creatinine (CREA), urea, glucose, amylase (AMY) and C-reactive protein (CRP) were measured within 1 hour from sample receipt. Leftover SF samples were then aliquoted in 5 aliquots and stored for 6 hours at room temperature (RT), and 3, 7, 14 and 30 days at -20 °C. At the end of each storage period all analytes were measured. Analytes were measured using the Abbott Architect c8000 (Abbott Laboratories, Abbott Park, USA). Mean bias was calculated for each parameter and respective storage period, and compared to stability limits (SL) set according to CROQALM criteria. Statistical analysis was performed using Medcalc (Ostend, Belgium). P < 0.05 was considered statistically significant. RESULTS: Significant differences comparing all storage periods were observed for LD, CREA, glucose and CRP (P < 0.001). Calculated biases for TP, ALB, CHOL, TRIG, CREA, urea, AMY and CRP in all storage periods tested were below the SL. Glucose and LD were stable for 6 hours at RT, with biases of -3.8 and 0.2%, respectively. Biases exceeding the SL were observed for glucose and LD in SF when stored for 3, 7, 14 and 30 days at -20 °C (i.e. -7.6, -11.5, -17.5 and -27.5% for glucose, and -17.1, -25.5, -30.1 and -40.3% for LD, respectively). CONCLUSIONS: Our results indicate that TP, ALB, CHOL, TRIG, CREA, urea, AMY and CRP may be safely analysed when SF samples are stored up to 6 hours at RT and/or 30 days at -20 °C. However, serous fluid glucose and LD are stable only up to 6 hours stored at RT.

preanalytical phase, stability, pleural fluid, peritoneal fluid

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