Blood work is important for a number of reasons. First of all, blood tests will show if your blood levels are within a normal range. If your blood levels go beyond the normal range, it could be because of a disease or disorder. Other factors that can affect blood levels include: - Physical activity level - Alcohol intake - Medications Getting routine blood work is essential for checking blood glucose and cholesterol levels, as well as diagnosing a number of diseases and conditions. Although some diseases and medical conditions cannot be diagnosed with blood work, knowing your blood levels can help you and your doctor learn more about your health.