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

Before a blood draw, the question of how much water you can drink is important for sample quality. For most routine blood tests (e.g., complete blood count, fasting glucose, lipid panel), clear still water in moderate amounts (200–400 ml) is allowed and even recommended to keep veins accessible and prevent dehydration. However, you must avoid sugary drinks, coffee, tea, milk, or juice, as they can alter blood sugar and lipid levels. For specific tests like an oral glucose tolerance test (OGTT) or strict fasting measurements (e.g., parathyroid hormone), only water without carbonation may be permitted – always follow your doctor's or lab's exact instructions. What you can do yourself: Drink a glass of water in the morning before the draw, remain fasting (no food for 8–12 hours), avoid strenuous exercise and smoking. These simple steps improve sample quality and reduce the need for repeats. Important: If in doubt, always adhere to your physician's specific guidance, as deviations can lead to inaccurate results.