Evidence check: CRP Entzündung in the context of fatigue

CRP (C-reactive protein) is a well-established biomarker for systemic inflammation, produced by the liver in response to interleukin-6. Elevated CRP levels (≥3 mg/L) are linked to chronic inflammatory states, which can be associated with fatigue. However, the evidence for a causal relationship between CRP and fatigue is moderate, primarily based on observational studies. Cross-sectional studies show a correlation between higher CRP and self-reported exhaustion, especially in conditions like rheumatoid arthritis or depression. Yet CRP is not a specific marker for fatigue; many individuals with elevated CRP are asymptomatic. Lifestyle factors such as poor sleep, obesity, or smoking can raise CRP and also contribute to tiredness. Commercial blood tests that promote CRP as a standalone indicator of fatigue are misleading. Clinical evaluation should include a thorough history and additional lab work. Safety note: CRP testing is useful for inflammation assessment but not for standalone fatigue workup. Evidence: human-moderate (observational studies).