wie erkenne ich, ob ein selbsttest wissenschaftlich fundiert ist? — when to see a doctor?

To assess whether a self-test is scientifically valid, check for: independent peer-reviewed studies, CE marking or FDA clearance, and reported sensitivity/specificity. Many direct-to-consumer (DTC) tests – especially DNA tests – rely on GWAS associations with small effect sizes that are often overstated. A single SNP (e.g., FTO for obesity) has minimal predictive power; lifestyle and environment matter far more. Hormone or microbiome tests from home samples can vary due to collection method and circadian rhythms. See a doctor if: (1) the test shows abnormal results, (2) you have symptoms (fatigue, weight changes, pain), (3) you need a diagnosis or treatment plan. Self-tests are screening tools, not diagnostic. Evidence for many DTC tests is weak or marketing-driven – be cautious of exaggerated claims.