How do we distinguish normal from abnormal? Are reference ranges the gold standard? Who do they identify? Where have they come from? For clinical practice that is increasingly dictated by guidelines and consensus statements accurate reference ranges are key to safe practice. Using examples of, amongst others, growth hormone, thyroid stimulating hormone and parathyroid hormone this talk will highlight the need for greater collaboration between laboratories, physicians and the diagnostics industry to enhance the evidence base for diagnostic cut-offs deployed in diagnosis and management of endocrine disorders. The overarching message is of a disconnect between purists aspirations for wholly accurate and reproducible assays, the diagnostics industrys need to maintain customer share in a commercial market and an often uncritical adoption by clinicians of new cut-offs as gold standards. The opportunity is for pragmatic approaches that may overcome our perpetuation of diagnosis and management based on weak evidence.