Fatigue is one of the most common reasons people visit their GP, and one of the hardest to investigate. The list of possible causes is long. You might be told to get more sleep, reduce stress, or that your blood tests are "normal". But in many cases, the right blood tests haven't been done, or the results haven't been interpreted with enough clinical depth. This article is a practical guide to the blood tests that are genuinely useful when fatigue is your primary symptom. Not