QC and clinical limits are different.
QC limits are set to control the process. For an assay with a high process capability clinical limits will always be much wider than QC limits. And for an assay that is out of control (values that exceed QC limits), results may still be within clinical limits. But it is nevertheless important to detect an out of control process because the process may become so out of control so that results fail clinical limits.
For a process that is in control (all values that within QC limits), can results be outside of clinical limits (potentially cause patient harm?) YES!
QC vs. Clinical Limits