Reference ranges are supplied strictly for guidance only, and these should be used rather than those quoted in textbooks, diaries etc, as both methods and units vary from department to department. These should not be published as methodology changes in line with the introduction of new techniques the ranges become outdated and therefore are subject to constant review. The current reference/therapeutic range is always included with the final report. 5% of the healthy population will have results marginally outside the quoted reference range. Ranges may be affected by age, gender, ethnic group, pregnancy, time of sampling and many other factors. Detailed information or advice on interpretation is always available from the laboratory.

Additional information regarding significant differences, for the most frequently requested Clinical Chemistry tests, is included. Significant differences are calculated from the analytical variance and biological variablity associated with each test and indicate the degree of change in sequential results that is likely to be significant.