TABLE 5.

Recommended QC procedures

Step no.	Procedure(s)
1	Establish in-house reference samples that represent normal and abnormal values encountered clinically. Prepare a large number of aliquots of these reference samples for frozen storage. Include each of these reference samples in every assay.
2	Test intra-assay variability in each run.
3	If single tests (rather than duplicate tests) are used, repeat 15% of randomly selected samples on the next run to establish comparability of replicates and interassay variability.
4	Test in duplicate the reference samples provided by the manufacturer.
5	Test reference (normal) populations each year and compare summaries of yearly results.