Tests
1st tests to order
serum thyroid-stimulating hormone (TSH)
Test
To rule out hyper- or hypothyroid-associated dementia.
Result
usually normal in DLB; TSH may be low or high
serum vitamin B12
Test
To rule out vitamin B12 deficiency-induced dementia.
Result
usually normal in DLB
CT head
Test
Neuroimaging is recommended in the workup of all cases of dementia, including DLB.[1][6]
CT head without intravenous contrast is useful in excluding tumors, normal pressure hydrocephalus, subdural hematoma, or vascular disease. In early Alzheimer disease, few changes are evident, although pronounced sulcal/gyral changes and global atrophy may be evident later in the disease.
Result
seldom normal in DLB
MRI head
Test
Neuroimaging is recommended in the workup of all cases of dementia, including DLB.[1][6]
MRI head without intravenous contrast is useful in excluding space-occupying lesions or other intracranial pathology.
Lower incidence of medial temporal lobe atrophy than in Alzheimer disease (AD).[6]
Generalized atrophy with temporoparietal predominance in AD; limited change in DLB.
Cerebral microbleeds are more abundant in DLB than AD in all brain areas except the occipital lobe.
Result
generalized cortical atrophy is typical, although may be mild with preservation of the medial temporal lobe, particularly the hippocampus
Tests to consider
CBC
Test
To rule out anemia.
Result
usually normal in DLB
metabolic panel
Test
Assessment of hypo- or hypernatremia, hypo- or hypercalcemia, hypo- or hyperglycemia, to rule out metabolic causes of dementia, and as an assessment for major organ failure affecting cognition.
Result
usually normal in DLB; ordered to exclude abnormal sodium, calcium, glucose levels
serum folate
Test
To rule out folate-associated cognitive changes.
Result
usually normal in DLB
serum Venereal Disease Research Laboratory
Test
To rule out syphilis as a cause of dementia.
Result
usually normal in DLB; may be positive in syphilis
urine drug screen
Test
To rule out recreational drug use including cannabis, cocaine, opioids, amphetamines, and benzodiazepines in appropriate patients, especially those with atypical syndromes.
Result
usually normal in DLB; may be positive when substance misuse is present
urinalysis
Test
To rule out urinary tract infection in cases of rapid cognitive decline or frequent fluctuations.
Result
usually normal; must be interpreted in light of other findings, such as adequacy of specimen, elevated WBC count, fever, and presence of indwelling catheters resulting in urinary tract colonization
HIV testing
Test
To rule out HIV infection as a cause of dementia in people at risk.
Result
may be positive
single-photon emission CT (SPECT)/positron emission tomography (PET)
Test
Functional imaging that can help distinguish between DLB and other types of dementia.[6][33]
Reduced dopamine transporter uptake in basal ganglia, demonstrated by SPECT or PET, has a sensitivity of 78% and specificity of 90% relative to Alzheimer disease.[1]
Occipital hypometabolism on F-18 fluorodeoxyglucose PET correlates with visual cortex pathology in DLB at autopsy.[1]
Result
low basal ganglia dopamine transporter uptake is a suggestive feature for DLB; occipital hypometabolism is often seen in DLB with PET
quantitative EEG
Test
Quantitative EEG with evidence of prominent posterior slow-waves with periodic fluctuation in the pre-alpha/theta range has been proposed as a DLB biomarker. It may distinguish from Alzheimer disease and may correlate with cognitive fluctuations. It may be seen when the patient has mild cognitive impairment.[28]
Quantitative EEG may not be widely available.
Result
may show prominent posterior slow-waves with periodic fluctuation in the pre-alpha/theta range
polysomnography
cerebrospinal fluid (CSF) analysis
Test
Should be ordered in patients with atypical features, such as rapid course.
Not routinely required, but may rule out infectious cause of dementia.
CSF tau levels are elevated and amyloid-beta 1-42 levels are decreased in Alzheimer disease compared with those in people with other forms of dementia and in adults without dementia. Alpha-synuclein levels are lower in DLB. CSF markers are not currently recommended in typical cases.
Result
normal in DLB
neuropsychological testing
Test
Neuropsychological tests are used to help quantify cognitive impairment and therefore aid in the diagnosis of dementias in general. Their use is not specific to DLB.
Global deficits with impairment in memory, attention, language, psychomotor performance, and executive function, with a particularly severe impairment in visuospatial and visuoconstructive abilities.
Alzheimer disease has more severe memory impairment.[34]
Result
visuospatial and visuoconstructive impairment more prominent in DLB
MIBG myocardial scintigraphy
Test
Abnormal (low uptake) 123-iodine-metaiodobenzylguanidine (MIBG) myocardial scintigraphy has high sensitivity and specificity for DLB, especially when compared to mild Alzheimer disease.[1]
Result
reduced cardiac uptake of 123-iodine-MIBG
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