Is IgE useful for Müdigkeit?

The provided context does not address IgE and fatigue. In general medicine, IgE is primarily a marker for allergic conditions and parasitic infections. Chronic allergies (e.g., hay fever, asthma) can contribute to fatigue via inflammation and sleep disruption, but routine total or specific IgE testing for non-specific fatigue lacks evidence. Sensitivity and specificity are low for fatigue as a symptom; other causes (iron deficiency, thyroid dysfunction, sleep apnea, mental health) are far more common. Consumer lab tests marketing IgE as an 'energy marker' should be viewed skeptically. Evidence is weak (mechanistic, no direct human trials). A physician should determine if IgE testing is indicated. Caveat: No clinical guideline recommends IgE as a standard test for fatigue.