wie lange kein kaffee vor blutabnahme — what are common causes?

Before a blood draw, it is generally recommended to avoid coffee for 8–12 hours, especially for fasting blood tests. Coffee can affect several lab values: it raises blood glucose, stimulates cortisol secretion, and can alter liver enzymes (e.g., GGT, ALT) and triglyceride levels. The tannins in coffee also inhibit iron absorption, which matters for iron panels. Even black coffee without milk or sugar can have these effects. Individual responses vary, so adhering to the fasting window is the safest approach. Caveat: This guidance is based on common medical practice rather than large-scale trials covering all analytes.