Vol. 11 No. 1

Organic and Functional Gastrointestinal Disorders: A Distinction Getting More Nebulous by the Day

June 2019

— Professor Sylvester Chuks Nwokediuko


With improvements in knowledge, occasioned by biomedical research, the classification of diseases into organic and functional disorders has become hazy and indeed questionable. This trend seems to affect the gastrointestinal system more than any other organ system.

Organic disorders are defined by distinct structural, physiological or biochemical alterations within the body and can be evaluated with standardized biological measures, called biomarkers. For functional disorders, there are no identifiable biological changes that can be measured.

Over time, many conditions that were hitherto classified as functional have been reclassified as organic when research findings shed more light on the processes involved. A typical example is achalasia, which was initially thought to be a functional disorder. With the demonstration of a reduction in non-adrenergic, non-cholinergic (NANC) inhibitory ganglion cells in the esophagus, the thinking changed.

A look at the pathophysiology and clinical phenotypes of gastroesophageal reflux disease (GERD) shows the vagueness inherent in the organic versus functional schema. Acid exposure and esophageal hypersensitivity are the 2 determinants of GERD symptomatology. It has been postulated that the influence of acid exposure decreases along the spectrum from reflux esophagitis, non-erosive reflux disease (NERD), reflux hypersensitivity and functional heartburn1. This means that acid exposure has great influence in the pathogenesis of reflux esophagitis but minimal or no influence in functional heartburn. Conversely, esophageal hypersensitivity is the major pathophysiologic mechanism in
functional heartburn and reflux hypersensitivity, but contributes minimally to erosive esophagitis. Using this schema, none of the phenotypes can be said to be truly organic or truly functional. This is the basis for the new name and definition of functional gastrointestinal disorders (FGIDs) in Rome IV criteria2. In the new system, the FGIDs are called disorders of gut-brain interaction and are defined as symptoms related to any combination of motility disturbance, visceral hypersensitivity, altered gut microbiota and altered central nervous system processing.


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The Nigerian Journal of Gastroenterology and Hepatology, is a bi-annual publication of the Society for Gastroenterology and Hepatology in Nigeria (SOGHIN), which publishes original research on the biology and diseases of the Gut, Liver, Pancreas, Peritoneum and Spleen both in humans and experimental animal models.

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