Investigation of fatigue.

Fatigue is a very common symptom and the cause can often be determined by careful history and physical examination. Since there is no organic cause for at least half of the cases of fatigue, extensive laboratory and radiological investigation may not be necessary. The minimal laboratory investigation should include a urinalysis, complete blood count, smear, sedimentation rate and chest X-ray. Further investigation will be determined by the presence of localizing symptoms and signs. If these are present, then only limited investigation may be necessary. If it is felt that the cause of the fatigue is organic and there are no localizing features, very extensive laboratory and radiological investigation will be required.