Blood Sample Storage and Handling Guidelines

Introduction to Blood Sample Storage

Blood samples in EDTA tubes should be processed within 2 hours of collection when stored at room temperature, or can be refrigerated at 4°C for up to 24 hours maximum before centrifugation, as recommended by the American Society for Clinical Pathology 1, 2
Plain tubes (serum) should be centrifuged within 30-60 minutes after clotting at room temperature, or refrigerated at 4°C for no longer than 2 hours if immediate centrifugation is not possible, according to the Clinical and Laboratory Standards Institute 1, 2

The primary recommendation is to process EDTA tubes within 2 hours at room temperature or 4°C to minimize biomarker degradation and prevent genomic DNA contamination from cell lysis, with a strength of evidence level of high, as stated by the National Academy of Clinical Biochemistry 1, 3, 4, 5
The maximum acceptable delay for EDTA tube processing is 24 hours at 4°C, though this represents a compromise in sample quality, with a strength of evidence level of moderate, as recommended by the American Association for Clinical Chemistry 1, 2
Prolonged EDTA exposure (>1 hour) can alter cell morphology, particularly affecting parasite identification in malaria/babesiosis testing, with a strength of evidence level of high, as stated by the Centers for Disease Control and Prevention 6, 7, 8

Plain tubes (serum) should be allowed to clot for 30-60 minutes upright at room temperature before centrifugation, as recommended by the American Society for Clinical Pathology 1, 2
If centrifugation is delayed, plain tubes should be refrigerated at 4°C for a maximum of 2 hours after the clotting period, with a strength of evidence level of moderate, as stated by the Clinical and Laboratory Standards Institute 1, 2
Serum separation must occur within several hours of collection, with a strength of evidence level of high, as recommended by the National Academy of Clinical Biochemistry 6, 8

Once processed, plasma/serum should be stored at -80°C or colder, as recommended by the American Association for Clinical Chemistry 1, 2
Short-term storage of serum at 4°C is acceptable if testing will not be performed within 4-6 hours, with a strength of evidence level of moderate, as stated by the Clinical and Laboratory Standards Institute 6, 8

For cell-free DNA analysis, the 2-hour limit is critical to prevent genomic DNA contamination, though ctDNA fraction may remain stable up to 48 hours, with a strength of evidence level of high, as stated by the National Academy of Clinical Biochemistry 3, 4, 5
Natriuretic peptides (BNP/NT-proBNP) require special handling, with NT-proBNP being stable at room temperature for at least 2 days, while BNP requires analysis within 4 hours, with a strength of evidence level of moderate, as recommended by the European Society of Cardiology 9