Hot Weather Alert: The current high temperatures across parts of the UK may affect the quality of blood samples sent through the post. If you are in an area with an extreme heat warning, please consider waiting until cooler conditions before collecting and returning your sample. If you need to test this week, please post your sample (Monday–Thursday) ideally at a post office, or as close to the advertised collection time as possible, to reduce the risk of heat-related sample degradation.