[Laboratory results in clinical practice: importance of interpretation in the clinical context]

Recently, a plenitude of novel laboratory tests has become available for physicians to improve the diagnostic and prognostic work up of patients. Yet, as with all tests, laboratory test can be falsely positive or falsely negative and potentially misguide clinicians and caregivers. Shortcomings of pre-analytical factors, test performance as well as an inappropriate ordering of laboratory tests contributes to diagnostic errors and potentially generate unnecessary costs. Laboratory tests should only be ordered, if results have clinical consequences and improve the assessment of the patient. Within this review focusing on the example of the inflammatory biomarker "Procalcitonin" for antibiotic stewardship and the hormonal marker testosterone, we aim to exemplify important draw backs and shortcomings in laboratory tests and the importance of interpretation of these results in the context of the clinical situation.