Laboratory testing is important for diagnosing and helping to manage health conditions. These might include blood tests, tests requiring samples of your urine or stool, and other services such as Pap tests and biopsies. Lab testing may be part of a routine check-up, help your doctor make a diagnosis, or be necessary for monitoring health conditions. If you have a chronic condition such as high cholesterol or diabetes, your doctor may ask you to come in regularly for tests to monitor your health. You may also request certain services yourself, such as screening for sexually transmitted infections.