[Validation of subjective complaints: differential diagnosis of "healthy suffering" using fatigue as an example].

Subjective complaints are of great importance in medicine. They have an impact on the diagnosis of illnesses, the assessment of illness severity, and treatment selection. There are no objective criteria for such symptoms, and clinicians have to rely on the report of patients only. Examples are complaints about pain, cardiac insufficiency, mood, or fatigue. There are many possibilities for distorted reports. Clinicians must therefore clarify what is meant and validate patient reports. A discrimination must be made between signs of illness and "healthy suffering," to avoid medicalization of daily nuisances and to avoid misdiagnoses and inadequate treatments. Diagnostic algorithms for healthy suffering are described, as this diagnosis is of importance in medicine. This is outlined using the example of fatigue.