Pharmakogenetik Medicheck: which blood markers matter?

The question 'which blood markers matter' in pharmacogenetics requires clarification. A pharmacogenetics test (e.g., Medicheck) typically analyzes DNA from blood or saliva to detect genetic variants affecting drug metabolism, not routine clinical blood markers like liver enzymes or creatinine. The key 'markers' are genetic variants: CYP2D6, CYP2C19, CYP3A4, TPMT, UGT1A1, SLCO1B1, VKORC1, etc. For specific drug-gene pairs (e.g., CYP2C19 with clopidogrel, TPMT with thiopurines), evidence is strong (human-strong per CPIC/DPWG guidelines). However, many consumer tests overstate clinical utility; effect sizes are often moderate, and dose adjustments also rely on blood levels, liver function (ALT, AST, GGT), and kidney function (creatinine, eGFR). A DNA test alone cannot replace regular therapeutic drug monitoring. Safety note: For narrow-therapeutic-index drugs (warfarin, thiopurines), routine blood tests are mandatory – genetics provides only partial guidance. Evidence: human-strong for well-established gene-drug pairs, but marketing-driven for many broad panels. Sources: none from provided context.