The diagnosis of psychosis is performed in a clinical setting. You may have to visit a doctor and get yourself evaluated. The first step to performing the diagnosis is a general observation of the patient. The doctor observes the patient objectively to see signs of confusions and disorientation.
The next step towards making the diagnosis is to give the person a psychological evaluation. This is a test to check for the mental acuity of the affected person. The test also helps the doctor determine the exact mental and emotional state that the patient is in. This would also help the doctor look for the symptoms associated with psychosis.
Though lab tests are usually not required for psychosis, sometimes, the doctor may see it fit to take a closer look at your brain. Some of the laboratory tests for psychosis include the MRI of the brain and an X ray of the skull. This helps the doctor check for any tumors or abnormal growths in the brain. This would also help the doctor determine if there are any particular anomalies in the brain structure. The doctor will also be able to make a better diagnosis.
Apart from these tests, the doctor may also screen you for drug use and other toxins that may affect the functioning of your brain. Since the symptoms of psychosis are very similar to those produced by syphilis, the doctor would most likely also ask you to be tested for syphilis.