At present, there is no special instrument or laboratory test that can directly confirm the diagnosis of Parkinson’s disease, but the clinical diagnosis has a compliance rate of 85%. Clinical diagnosis means that the doctor can diagnose or exclude Parkinson’s disease according to the clinical manifestations of the patient, combined with some instruments and biochemical tests. The following are 3 important laboratory tests for diagnosing Parkinson’s disease: 1. Laboratory tests of cerebrospinal fluid are more important. Patients have reduced levels of homovanillic acid (HVA), a metabolite of dopamine, in their cerebrospinal fluid. 2, Urinalysis will also show decreased excretion of homovanillic acid. 3. In order to differentiate from Parkinson’s syndrome, in addition to cerebrospinal fluid tests, some hematologic tests are often needed for the clinician to make a differential diagnosis and guide treatment. (1) Blood tests for aminotransferases and non-protein nitrogen can help identify patients with liver and kidney insufficiency. (2) The measurement of antiviral antibodies in the blood can check whether a patient has had a viral infection. (3) Blood tests can also provide blood concentrations of metal ions such as copper, mercury, and manganese, whose abnormal levels in the body are one of the major causes of Parkinson’s syndrome. (4) Serum renin activity is reduced, tyrosine levels are reduced; NE and 5-HT levels are reduced in the substantia nigra and striatum, and glutamic acid decarboxylase (GAD) activity is reduced by 50% compared to controls. (5) If the patient is suspected of having taken an overdose of a therapeutic substance, the blood concentration of the substance can be detected in the blood (the original form of the substance or its metabolites can also be detected in the urine). (6) If the patient has endocrine metabolic abnormalities, blood tests can provide levels of endocrine hormones or other metabolites.