Evidence-based diagnosis in endocrinology Roman Jaeschke, MD, MSc a , Gordon H. Guyatt, MD, MSc a,b, * , Victor M. Montori, MD, MSc c a Department of Medicine, McMaster University, 1200 Main Street West, Hamilton, Ontario, L8N 3Z5, Canada b Department of Clinical Epidemiology and Biostatistics, McMaster University, 1200 Main Street West, Hamilton, Ontario, L8N 3Z5, Canada c Division of Endocrinology, Metabolism, Nutrition, and Internal Medicine, Mayo Clinic, 200 First Street Southwest, Rochester, MN 55905, USA Anyinteractionwithpatientsinvolvesoneormoretasksthatmayinclude establishing and communicating the prognosis of a particular condition, choosing, if available, an appropriate therapy or preventive strategy, and supporting them during therapy. This chain of events clearly begins with a determination of what is happening, that is, establishing the diagnosis. A rapidly growing literature that describes the characteristics and useful- ness of diagnostic tests and procedures provides information that can help clinicians make an accurate diagnosis. The concepts used in this literature (andthevocabularyusedtodescribethem)arereviewedinthisarticle.They are introduced in the context of a clinical scenario that describes the testing of a urine sample for the presence of microalbuminuria. Recent guidelines for the management of diabetes recommend that patientshaveannualscreeningforproteinuria.Thepresenceofevenasmall amount of protein in urine (microalbuminuria) has important prognostic and therapeutic implications. Twenty-four–hour urine collections for albu- min remain the gold standard for detecting microalbuminuria, but they are quite cumbersome, and the need for a simpler, more convenient test is obvious. A determination of the urine albumin concentration (UAC) or the urine albumin:creatinine ratio (UACR) in a random urine sample is an appropriateoption.Thiswasassessedina1997article[1]thatdescribedthe Endocrinol Metab Clin N Am 31 (2002) 567–581 * Corresponding author. E-mail address: guyatt@mcmaster.ca (G.H. Guyatt). 0889-8529/02/$ - see front matter Ó 2002, Elsevier Science (USA). All rights reserved. PII:S0889-8529(02)00018-X