When it comes to sample integrity, the clock starts ticking as soon as the sample of interest leaves the body. To be able to accurately assess the presence and/or concentration of an intended measurand, all efforts must focus on retaining the quality and integrity of the sample.
The period between sample collection and arrival in the laboratory is called transport time. The goal for optimal sample integrity is to minimize the transport time, as the clock continues to tick during the sample preparation phase prior to analysis. Prolonged blood sample transport time may result in false decreases in glucose, where delay in centrifugation may cause continued metabolism, or false increases in potassium and magnesium, which are highly prevalent within red blood cells.
When samples may be delayed during transport to the laboratory, measures to control temperature may be implemented. This will be discussed in greater detail on the next page.