Storage of human serum sample in a refrigerated or non-refrigerated environment is dependent on the kind of test you want to perform. The storage of serum sample in non-refrigerated environment could be minimized and sample must be used as early as possible in order to rule out any undesirable possibilities. Even the refrigeration of human serum sample may be useful for few days to week time. However, long term storage (for month to year) could be avoided. However, for certain test (parameters), even the long storage at -80C or liquid Nitrogen can be done.

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