What labs for new onset tremor?

From the Guidelines

Laboratory Evaluation for New Onset Tremor

New onset tremor requires a thorough laboratory evaluation to determine the underlying cause, and initial labs should include a complete blood count, comprehensive metabolic panel, liver function tests, and thyroid function tests 1.

• These tests can help identify potential causes of tremor such as thyroid disorders, electrolyte imbalances, or liver disease.
• Additionally, serum electrolyte levels, including calcium, magnesium, and potassium, should be assessed to rule out electrolyte imbalances that can cause tremors.
• If medication-induced tremor is suspected, a review of the patient's medication list should be performed, with particular attention to medications such as lithium, valproic acid, and selective serotonin reuptake inhibitors, which can cause tremors at therapeutic doses.
• In some cases, imaging studies such as I-123 ioflupane SPECT/CT may be useful to differentiate Parkinsonian syndromes from essential tremor and drug-induced tremor, demonstrating abnormality early in the disease course compared with anatomic imaging such as standard CT or MRI 1.
• However, these advanced imaging studies are not typically part of the initial laboratory evaluation and are usually reserved for cases where the diagnosis is unclear or where Parkinsonian syndromes are suspected.

From the Research

Diagnostic Approach for New Onset Tremor

To diagnose new onset tremor, a stepwise approach can be taken, which includes a detailed history and physical examination, followed by laboratory tests and imaging studies as needed. The following are some of the key points to consider:

• A thorough history and physical examination can help identify the type of tremor and its underlying cause 2, 3
• Laboratory tests such as neurophysiology, structural and dopaminergic imaging, and genetic testing may be ordered to rule out underlying conditions such as metabolic disorders, drug-induced tremor, or genetic mutations 2, 3
• The distinction between isolated and combined tremor syndromes can inform the selection of appropriate diagnostic tests 2

Laboratory Tests for New Onset Tremor

Some of the laboratory tests that may be ordered for new onset tremor include:

• Neurophysiology tests such as electromyography (EMG) and electroencephalography (EEG) to evaluate muscle and nerve function 2
• Structural imaging tests such as magnetic resonance imaging (MRI) or computed tomography (CT) scans to evaluate brain structure and rule out underlying conditions such as stroke or tumor 2, 3
• Dopaminergic imaging tests such as positron emission tomography (PET) scans to evaluate dopamine function in the brain 2, 3
• Genetic testing to evaluate for genetic mutations that may be associated with tremor disorders 2, 3

Common Causes of New Onset Tremor

Some of the common causes of new onset tremor include:

• Essential tremor, which is a common movement disorder characterized by action tremor 4, 3
• Parkinson's disease, which is a neurodegenerative disorder characterized by resting tremor, bradykinesia, and rigidity 4, 5
• Drug-induced tremor, which can be caused by certain medications such as beta blockers, antidepressants, and antipsychotics 4, 3
• Metabolic disorders such as hypothyroidism, hyperthyroidism, and liver disease, which can cause tremor as a symptom 2, 3