Most Commonly Ordered Lab Tests By Neurologists

Neurological testing is essential in diagnosing conditions that affect the brain, spinal cord, and nerves. Lab tests, in particular, help neurologists gather essential information about a patient’s health and identify the underlying causes of neurological symptoms, such as seizures, confusion, muscle weakness, or memory problems. 

This article informs patients and healthcare professionals about tests commonly ordered by neurologists and how their results assist in diagnosing and treating neurological conditions. 

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Blood Tests Commonly Ordered by Neurologists

Lab tests provide essential information about a patient’s overall health and can detect issues that might cause or worsen neurological symptoms. Below are some of the most frequently ordered blood tests by neurologists:

1. Complete Blood Count (CBC)

A CBC checks the levels of different blood cells, such as red and white blood cells and platelets. This test helps identify infections, anemia, or other conditions that can cause symptoms like fatigue, weakness, or confusion. These issues may be linked to neurological problems.

2. Electrolyte Panel

‍An electrolyte panel measures the balance of minerals in the blood, such as sodium, potassium, and calcium. Electrolyte imbalances can lead to seizures, confusion, muscle weakness, and other neurological symptoms.

3. Liver Function Tests (LFTs)

‍LFTs help identify liver problems. When the liver doesn’t work properly, it can lead to hepatic encephalopathy, where toxins build up in the blood and affect brain function. This can result in confusion, mood changes, and cognitive problems.

4. Thyroid Function Tests

‍Thyroid function tests measure hormone levels produced by the thyroid gland. Imbalances in these hormones can affect cognition and mood and even cause memory problems or depression, all of which are linked to neurological health.

5. Inflammatory Markers (ESR, CRP)

‍Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are used to detect inflammation in the body. High levels of these markers may suggest autoimmune or inflammatory diseases, which can lead to neurological symptoms such as pain, weakness, or numbness.

Cerebrospinal Fluid (CSF) Analysis

Cerebrospinal fluid (CSF) analysis helps diagnose various brain and spinal cord conditions. This test involves collecting a small sample of the fluid surrounding the brain and spinal cord to look for signs of infection, inflammation, bleeding, or other abnormalities.

Lumbar Puncture (Spinal Tap) - A lumbar puncture (spinal tap) is used to collect CSF. During a lumbar puncture, a doctor inserts a thin needle into the lower part of the spine to draw out a small amount of CSF. This fluid is then sent to a lab for analysis. 

A lumbar puncture can help detect:

• Infections like meningitis  
• Bleeding in the brain 
• Multiple sclerosis or other nerve disorders  

Metabolic and Genetic Tests

Neurologists use metabolic and genetic tests to diagnose conditions that affect the brain, nerves, or muscles. These tests can provide important information about whether a person has an inherited condition or a metabolic disorder that could be causing neurological symptoms.

Metabolic Panels

A metabolic panel is a blood test that checks how well the body’s metabolism is working. It measures things like sugar levels, proteins, and enzymes. Some metabolic disorders, like Wilson’s disease, cause harmful substances to build up in the body, which can lead to neurological problems like tremors, muscle stiffness, or memory loss. Detecting these disorders early can help prevent severe brain or nervous system damage.

Genetic Testing

Genetic testing looks for specific changes or mutations in a person’s genes that might cause neurological diseases. Some conditions, like Huntington’s disease or certain types of epilepsy, are inherited. Identifying genetic causes allows neurologists to provide more personalized treatment plans and, in some cases, offer preventive measures for family members at risk of developing the same disorder.

Autoimmune and Infectious Disease Tests

Neurologists often use tests to check for autoimmune and infectious diseases that can impact the nervous system. 

Antinuclear Antibody (ANA) 

The antinuclear antibody (ANA) test screens for autoimmune disorders. It checks for antibodies that attack the body’s own cells. If these antibodies are found, it may indicate the presence of an autoimmune disorder. Conditions like lupus and multiple sclerosis can cause neurological symptoms such as numbness, tingling, or vision problems. 

Infectious Disease Panels‍

Infectious disease panels detect infections that may lead to neurological problems. Certain infections, like HIV and Lyme disease, can cause inflammation or damage to the brain and nerves, leading to conditions like encephalitis (brain inflammation) or neuropathy (nerve damage). 

Testing for infections is critical because early diagnosis and treatment can prevent or minimize long-term neurological damage. For instance, untreated Lyme disease can lead to memory issues or facial paralysis, while untreated HIV can cause severe brain disorders.

Electromyography (EMG) and Nerve Conduction Studies (NCS)

EMG and NCS are used to evaluate the health of muscles and nerves. These tests measure the electrical activity in muscles and the speed at which nerves send signals. They are useful for diagnosing neuromuscular disorders, which are conditions that affect how the nerves and muscles work together.

• EMG involves inserting a small needle electrode into the muscle to record electrical signals. This helps neurologists understand if the muscle is responding normally or if there is a problem in the communication between nerves and muscles. 
• NCS is a non-invasive test that involves placing electrodes on the skin to measure how quickly and effectively nerves send electrical signals.

EMG and NCS are used to diagnose conditions such as:

• Peripheral neuropathy, where nerves in the hands or feet are damaged, causing symptoms like numbness or tingling. 
• Myasthenia gravis is another condition that can be diagnosed with EMG, where the connection between nerves and muscles weakens, leading to muscle fatigue. 
• Amyotrophic lateral sclerosis (ALS), a progressive disease affecting nerve cells in the brain and spinal cord, can also be identified with these tests.

Neuroimaging-Related Lab Tests

Neuroimaging tests like MRI and PET scans provide detailed anatomical images that help neurologists pinpoint abnormalities and determine the best course of treatment.

Magnetic Resonance Imaging (MRI) with Contrast

‍A MRI is used to visualize the brain in great detail. The "contrast" refers to a special dye injected into the bloodstream before the scan. This dye enhances the images, making it easier to see abnormalities in the brain, such as tumors, strokes, or multiple sclerosis lesions. 

The contrast dye highlights areas with abnormal blood flow or where the blood-brain barrier has been compromised, which can happen in various neurological conditions. For example, in MS, the contrast can show active inflammation and damage to the myelin sheath, which helps neurologists track the progression of the disease.

Positron Emission Tomography (PET) Scan‍

A PET scan measures the brain's metabolic activity, offering insights into how the brain is functioning rather than just its structure. PET scans are especially helpful in diagnosing diseases like Alzheimer’s and Parkinson’s, where brain activity changes before structural damage is visible. 

For example, in Alzheimer’s disease, PET scans often show areas of reduced glucose metabolism, which correlates with memory and cognitive decline. Similarly, PET scans can identify changes in the brain’s dopamine system, which is key for diagnosing Parkinson’s disease.

Brain Computed Tomography (CT)

‍A brain CT scan is a fast, non-invasive imaging test used to detect and diagnose various neurological conditions. It provides detailed cross-sectional images of the brain, helping doctors identify issues like bleeding, strokes, tumors, and skull fractures. 

CT scans are especially useful in emergency situations, such as after head trauma, because they can quickly show areas of bleeding or swelling. While less detailed than MRI, Brain CT scans are often the first step in diagnosing conditions requiring immediate medical attention, providing critical information to guide urgent treatment.

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Key Takeaways

Neurologists use various blood and imaging tests to diagnose neurological conditions.

• Complete Blood Count (CBC) helps detect infections, anemia, and other conditions affecting neurological health.
• The electrolyte panel identifies imbalances that may cause seizures or confusion.
• CSF analysis via lumbar puncture is used to diagnose infections, multiple sclerosis, and other brain conditions.
• Metabolic and genetic tests are critical for diagnosing inherited or metabolic neurological disorders, such as Huntington's disease or Wilson’s disease.
• Autoimmune and infectious disease tests, such as ANA and infectious disease panels, screen for conditions like lupus or Lyme disease.
• EMG and Nerve Conduction Studies (NCS) assess nerve and muscle health, diagnosing conditions like peripheral neuropathy and ALS.
• Neuroimaging tests like MRI with contrast and PET scans provide detailed views of brain structure and function for conditions like tumors, strokes, and Alzheimer's disease.