Prevalence of symptoms

Although upper abdominal and epigastric pain is extremely common and hence a poor discriminator of disease, only 2-8% of the general population experience anorexia, nausea, and vomiting, and so these are much more likely to indicate disease. Thankfully, many of these events turn out to be short lived, and only about 25% of those affected consult their general practitioner, but this still accounts for 1-2% of all consultations in general practice.

Two thirds of patients give the severity of their symptoms as a reason for consulting, but a similar proportion consult because of fear of serious disease, a factor that must be considered when planning management. The challenge is to reliably sift out and satisfactorily reassure the 40% with functional disease without missing those with more serious pathology.

Pathophysiology

Anorexia, nausea, and vomiting with pain can all be regarded teleologically as protective reflexes whereby the body prevents the entry of toxins into the body. They also reduce the passage of chyme through diseased parts of the upper gut, thereby minimising further pain.

There are many possible organic causes, but, because there is an important central component, these behaviour patterns can be learnt and may be anticipatory. Thus, patients about to receive chemotherapy may vomit at the sight of the drugs, which they have previously associated with vomiting. Anxiety and depression can also be associated with alterations in taste—with associated anorexia, nausea, and weight loss—through neural pathways as yet poorly defined.

Pharmacology

Toxins and hypertonic saline induce vomiting by …