wie viel wasser trinken vor blutabnahme — what can you do yourself?

How much water to drink before a blood draw depends on the specific test. For most routine blood tests (e.g., complete blood count, basic metabolic panel), drinking up to one glass (about 200 ml) of plain water is generally considered safe, even when fasting is required. However, for strict fasting tests (e.g., glucose, lipid panel), water intake should be minimal or avoided, as even small amounts can affect results. Drinking too much water (>500 ml) can dilute the blood and alter values like hematocrit or sodium. Important: No coffee, tea, juice, or milk – only still water. The best approach is to ask your doctor or lab beforehand whether water is allowed. Self-administering large amounts is not recommended. Evidence: practice-based, limited strong clinical studies.