How does one interpret a marginally abnormal serum chemistry test?

There are factors, independent of illness, that affect the interpretation of reported concentrations of serum constituents. These include normal ranges and how they are determined, the influence of intraindividual and interindividual biological variability, and the analytical variability in the clinical laboratory. There are factors that may affect the concentration of some of the most commonly measured serum constituents; these should be considered when the marginally abnormal result is examined.