A doctor or other healthcare professional commonly obtains a diagnosis, which begins with a physical examination and an investigation of the patient's history. Following that, testing and other diagnostic procedures are suggested to establish the underlying sickness or damage producing the symptoms. Testing may include laboratory studies, imaging tests, and/or biopsies. In some cases, a diagnosis can be made based on clinical findings alone; in others, additional testing is needed. For example, if a patient comes into the office with pain in their chest, shoulder, back, or jaw, but has no past medical history indicating anything wrong with them, a doctor would first do a complete physical examination before making any assumptions about what might be causing the problem. If everything else was normal, then the doctor might suggest some basic tests, such as blood panels or x-rays, to rule out any possible underlying conditions that could cause these symptoms. In most cases, a diagnosis is made by a physician after a comprehensive assessment of all available information. The physician may consult various reference sources, including books and journals, to obtain information about diseases that may have similar symptoms. Diagnoses are important because they guide health professionals and patients toward appropriate treatments. It is also important to note that not all people who are diagnosed with the same illness will need the same type or amount of therapy.