The main risks of blood tests are discomfort and bruising at the site where the needle is inserted. These issues usually are minor and go away shortly after the tests are done.
Clinical trials are research studies that explore whether a medical strategy, treatment, or device is safe and effective for humans.
The NHLBI updates Health Topics articles on a biennial cycle based on a thorough review of research findings and new literature. The articles also are updated as needed if important new research is published. The date on each Health Topics article reflects when the content was originally posted or last revised.