External quality assurance of test requesting and test interpretation

The ultimate product of the clinical laboratory is not a number, but an adv ice. To what quality standards should this advice live up to? In external q uality assurance for primary health care in Norway, case histories are mail ed together with the analytical quality control material. The analytical re sult of the control material is used in the case history. The feedback repo rts discuss clinical guidelines as well as the influence of analytical vari ation on clinical decisionmaking.