Blood tests can help detect and diagnose various diseases and conditions. Some common examples include: anemia, infections, such as bacterial or viral infections, liver and kidney disorders, diabetes and blood sugar imbalances, thyroid problems, certain cancers, autoimmune disorders, and sexually transmitted diseases (STDs) like HIV or syphilis. However, it's important to remember that blood tests are not comprehensive for all diseases, and specific tests are often required for accurate diagnosis. Healthcare professionals use blood tests in conjunction with other clinical evaluations and medical history to make an accurate diagnosis.