Diagnostic procedures: Functional tests and post-mortem protocol

Abstract

Functional tests are dynamic investigations based on the measurement of intermediary metabolites in body fluids. They are most useful in disorders that give rise to toxicity or energy deficiency. The best functional test is elicited by nature itself during episodes that cause metabolic stress, including acute infection, inadvertent fasting, or consumption of a nutrient that induces a metabolic intolerance. If an inherited metabolic disease is suspected then blood, urine and cerebrospinal fluid should be collected for the appropriate investigations (Chapter 1, Table 1.3). If no material is available or if the results are ambiguous, a provocative test that challenges a metabolic pathway may provide clues to a diagnosis and indicate which specific enzymatic or genetic analysis should be undertaken.