Introduction: Who Should Seek Diagnosis and When

If you’ve noticed unusual sensations in your hands or feet — perhaps a tingling feeling, numbness, or sharp pains that seem to come out of nowhere — it may be time to talk to your doctor. Peripheral neuropathy affects millions of people worldwide, and early diagnosis can make a significant difference in managing the condition and preventing it from getting worse.^[1]

You should seek medical attention if you experience pain, tingling, or loss of sensation in your feet, loss of balance or weakness, or if you have a cut or ulcer on your foot that isn’t healing properly. These symptoms often start gradually in the feet and may eventually spread upward into the legs, and later to the hands. The sooner you see a healthcare provider, the better your chances of limiting damage and preventing complications.^[4]

People with certain health conditions are at higher risk and should have regular check-ups even if they don’t yet have symptoms. This is particularly important for people with diabetes, as high blood sugar levels over time can damage nerves. In fact, diabetes is the most common cause of peripheral neuropathy in many countries. Other conditions that increase your risk include rheumatoid arthritis, lupus, kidney disease, thyroid problems, and a history of heavy alcohol use or exposure to certain toxins or medications.^[5]

It’s important not to ignore early symptoms. Many people think that occasional tingling or numbness is just a minor inconvenience, but without proper diagnosis and treatment, peripheral neuropathy can become a progressive disease. This means symptoms may worsen over time, potentially leading to permanent nerve damage, severe pain, loss of mobility, or serious complications like foot ulcers and infections.^[18]

Classic Diagnostic Methods

Diagnosing peripheral neuropathy involves a step-by-step process that begins with your doctor learning about your health history and symptoms. Your healthcare provider will want to know when your symptoms started, where you feel them, how severe they are, and whether anything makes them better or worse. They’ll also ask about your lifestyle, including alcohol consumption, any medications you take, potential exposure to toxic chemicals, and whether anyone in your family has a history of nerve diseases.^[8]

A thorough physical and neurological examination is one of the first diagnostic steps. During this exam, your doctor will check your tendon reflexes (the automatic responses your muscles make when tapped), muscle strength and tone, your ability to feel sensations like touch, temperature, and vibration, and your balance and coordination. These simple tests help determine which nerves are affected and how severely.^[8]

Blood tests are commonly ordered to look for underlying causes of nerve damage. A complete blood count can reveal signs of infection or inflammation. A comprehensive metabolic profile checks for kidney, liver, or metabolic problems. Tests for fasting blood glucose and hemoglobin A1C help diagnose or monitor diabetes. Vitamin B12 levels are measured because deficiency can cause nerve damage. Thyroid-stimulating hormone tests check for thyroid dysfunction, and serum protein electrophoresis with immunofixation looks for abnormal proteins that might indicate certain diseases.^[5]

When the initial evaluation doesn’t reveal a clear cause, or if symptoms are concerning — such as rapid onset, symptoms affecting only one side of the body, or primarily motor or autonomic symptoms — your doctor may recommend electrodiagnostic studies. These tests measure how well your nerves are working. An electromyography (EMG) test measures electrical activity in your muscles. During the test, a thin needle electrode is inserted into the muscle to record activity as you contract it. This helps find nerve damage.^[8]

Usually performed along with EMG is a nerve conduction study. For this test, flat electrodes are placed on your skin, and a low electric current stimulates the nerves. Your doctor records how the nerves respond to this current. These combined tests help determine whether nerve damage is axonal (affecting the nerve fiber itself) or demyelinating (affecting the protective coating around nerves). This distinction can help identify the cause and guide treatment.^[8]

In some cases, additional nerve function tests may be performed. An autonomic reflex screen records how the autonomic nerve fibers work — these are the nerves that control functions you don’t consciously think about, like blood pressure, heart rate, and digestion. A sweat test measures your body’s ability to sweat, and sensory tests record how you feel touch, vibration, cooling, and heat.^[8]

Imaging tests such as CT scans (computed tomography) or MRI scans (magnetic resonance imaging) are not routinely used to diagnose peripheral neuropathy. However, they can be helpful in specific situations to look for herniated disks, compressed nerves, tumors, or other problems affecting blood vessels and bones that might be pressing on nerves. These imaging tests are more useful when symptoms suggest a problem with nerve roots near the spine or with nerve bundles in other areas.^[8]

In rare cases, when other tests haven’t provided a clear answer, your doctor may recommend a nerve biopsy. This involves removing a small piece of peripheral nerve tissue, usually from the lower leg, to examine under a microscope. While this can provide valuable information about the type and severity of nerve damage, it’s an invasive procedure and is typically reserved for complex or unclear cases.^[8]

The diagnostic process aims to identify not just that you have peripheral neuropathy, but also what’s causing it. Peripheral neuropathy is idiopathic — meaning the cause cannot be identified — in about 25% to 46% of cases. However, when a cause can be found, treatment options often become clearer. Common identifiable causes include diabetes, nerve compression or injury, alcohol use, toxin exposure, hereditary diseases, nutritional deficiencies, certain medications, and various infections or autoimmune conditions.^[5]

Diagnostics for Clinical Trial Qualification

When patients are being considered for participation in clinical trials studying peripheral neuropathy or treatments for conditions that may cause it, additional or more specific diagnostic tests may be required. Clinical trials often have strict criteria for who can participate, and these standards help researchers collect reliable data and ensure patient safety.

Standard initial laboratory tests used for clinical trial qualification typically mirror those used in routine diagnosis. These include a complete blood count, comprehensive metabolic profile, fasting blood glucose levels, vitamin B12 levels, thyroid-stimulating hormone tests, and serum protein electrophoresis with immunofixation. These tests establish baseline values and help rule out certain causes or complications that might affect trial participation or results.^[5]

Electrodiagnostic studies, including EMG and nerve conduction studies, are frequently required for clinical trial enrollment. These tests provide objective measurements of nerve function that can be used to assess whether a patient meets the trial’s inclusion criteria. They also establish a baseline against which any changes during the trial can be measured. The results help researchers categorize the type and severity of neuropathy, which is important for understanding how different patients respond to experimental treatments.^[8]

For some research studies, particularly those investigating new medications or therapies, specific antibody assays or other specialized blood tests may be requested. These tests might look for markers of inflammation, immune system activity, or specific disease processes. The exact tests required depend on the nature of the clinical trial and what the researchers are studying.

Documentation of the underlying cause of neuropathy is often essential for trial qualification. If diabetes is the cause, for example, researchers may require specific blood sugar measurements or A1C test results showing that diabetes is controlled within a certain range. If the neuropathy is related to chemotherapy or another medication, detailed medical records documenting treatment history may be needed.

Some trials may require imaging studies to ensure there are no other conditions that could complicate the research or put the patient at risk. While not typically needed for straightforward peripheral neuropathy diagnosis, MRI or CT scans might be requested in clinical trial settings to rule out structural problems or other nerve conditions.

Regular monitoring and repeat testing throughout the trial period are standard practice. Participants typically undergo the same diagnostic tests multiple times — at the beginning, during, and at the end of the study — to track changes and evaluate whether the experimental treatment is working. This systematic approach helps researchers gather the evidence needed to determine if new treatments are safe and effective.