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Diagnosis of Parkinson’s Disease

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The diagnosis continues to be clinical and, therefore, is based on the interview (anamnesis) and the physical examination. However, in some circumstances, such as unusual ages of presentation, the presence of tremor only with no other signs or symptoms, or other clinical abnormalities, complementary tests can help rule out other causes or diseases, and to confirm the diagnosis.

Blood tests. There is currently no blood test that can help diagnose Parkinson’s disease. However, in cases where tremor predominates, it is recommended to perform a thyroid profile in order to rule out thyroid disorders. It is also recommended in cases when the disease starts when the person is young, to determine copper metabolism to help rule out Wilson’s disease, which has a specific treatment.

Laboratory tests of other biological fluids. Currently, neither the analysis of urine, nor saliva, nor cerebrospinal fluid can diagnose the disease, but there are a multitude of experimental biomarkers, mainly in cerebrospinal fluid, that could be of diagnostic use in the future.

Structural Neuroimaging. If symptoms are atypical and, as is usually the case at onset, occur on only one side, a structural imaging test (CT scan or MRI) can be carried out to rule out structural lesions in one cerebral hemisphere, explaining symptoms limited to the opposite side of the body and ruling out other structural alterations (vascular lesions, hydrocephalus) that may occur with parkinsonism.

Functional neuroimaging. Single photon emission computed tomography (SPECT) imaging of dopamine transporter is available in order to determine the reduction in the amount of dopamine in the striate (part of the basal ganglia that receives the dopamine of the black substance), as an indirect measurement of the decrease of dopamine in the black substance. It is not a specific diagnostic test of Parkinson’s disease, since it is altered by any neurodegenerative type Parkinsonism. It should be reserved for cases in which it may be used to make a differential diagnosis between Parkinson’s disease and secondary non-degenerative type Parkinsonism (vascular, pharmacological), or essential tremor. In cases in which the Parkinsonism is associated with significant cognitive impairment and there is a doubt between dementia of Parkinson’s disease and Alzheimer’s disease, an altered SPECT of dopamine transporter confirms the possibility of Parkinson’s dementia.

Substantiated information by:

Almudena Sánchez Gómez

Ana Cámara Lorenzo

Maria José Martí Head of the Parkinson's and Movement Disorders Unit

Yaroslau Compta Hirnyj Neurologist Neurology Service

Published: 8 July 2019
Updated: 14 November 2019

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