Orris

Patient comes with burning sensation in feet what tests should be done?

Reading File
Finding Sources
Finding Sources
Searching PubMed

"burning feet" OR "burning sensation feet" peripheral neuropathy diagnosis

Finding Sources
Finding Sources
Searching PubMed

"peripheral neuropathy" diagnosis workup evaluation

Finding Sources
Finding Sources
Reading File
Reading File
Finding Sources
Finding Sources
Reading File
Reading File
Reading File
Reading File
Reading File
Finding Sources
Reading File
Reading File
Finding Sources
I now have enough information from the textbooks to give a thorough, well-organized answer. Let me compile this.

Workup for a Patient with Burning Sensation in the Feet

Burning feet is a classic presentation of small-fiber or mixed peripheral neuropathy, most commonly a length-dependent sensory polyneuropathy. The evaluation follows a tiered approach: history + examination first, then targeted investigations.

Step 1 - Clinical Context (Before Ordering Tests)

Ask about:
  • Duration, progression, bilateral vs. unilateral
  • Associated numbness, weakness, or balance problems
  • Diabetes, alcohol use, chemotherapy, HIV, malnutrition
  • Family history (hereditary neuropathies like CMT)
  • Medications (metronidazole, isoniazid, statins, thalidomide, taxanes)
  • Systemic symptoms (weight loss, fatigue, rash)

Step 2 - First-Line Blood Tests (Routine Screen)

These should be ordered for virtually every patient:
TestWhat it screens for
Fasting blood glucose / HbA1cDiabetes (most common cause, ~50% of cases)
Oral glucose tolerance test (OGTT)Prediabetes (impaired glucose tolerance) - found in >50% of "cryptogenic" neuropathy
Complete blood count (CBC)Anemia, macrocytosis (B12 deficiency), hematologic malignancy
Comprehensive metabolic panelRenal failure (uremic neuropathy), liver disease
Serum vitamin B12B12 deficiency (subacute combined degeneration)
Thyroid-stimulating hormone (TSH)Hypothyroid neuropathy
ESR / CRPSystemic inflammation, vasculitis
Serum protein electrophoresis (SPEP) + immunofixationMonoclonal gammopathy (MGUS, myeloma, amyloid)
"Burning usually suggests preferential injury to small-diameter axons." - Goldman-Cecil Medicine, p. 4075

Step 3 - Second-Line Tests (Based on Clinical Suspicion)

If diabetes/prediabetes suspected but glucose normal:
  • 2-hour OGTT (unmasks impaired glucose tolerance)
If B12 borderline (200-400 pg/mL):
  • Methylmalonic acid + homocysteine (more sensitive markers of functional B12 deficiency)
  • Serum folate
If autoimmune/inflammatory neuropathy suspected:
  • ANA, ANCA, anti-dsDNA
  • Anti-SSA/SSB (Sjogren's syndrome - a common underdiagnosed cause)
  • ANCA (vasculitic neuropathy)
  • Cryoglobulins
  • Rheumatoid factor
If paraproteinemia found:
  • 24-hour urine protein electrophoresis (UPEP)
  • Urine immunofixation
  • Serum free light chains
  • Bone marrow biopsy (if myeloma suspected)
If HIV risk factors / infectious causes:
  • HIV serology
  • RPR/VDRL (syphilis)
  • Lyme serology (in endemic areas)
If nutritional deficiency / malabsorption:
  • Vitamin E, copper levels
  • Thiamine (B1) - especially in alcoholics
If hereditary neuropathy suspected (young patient, family history, pes cavus, hammer toes):
  • Genetic testing for CMT (Charcot-Marie-Tooth) - PMP22 duplication most common
If amyloidosis suspected:
  • Abdominal fat aspirate or skin biopsy with Congo red staining
  • Transthyretin (TTR) gene testing

Step 4 - Electrodiagnostic Studies

Nerve conduction studies (NCS) + Electromyography (EMG)
  • The cornerstone of peripheral neuropathy evaluation
  • Distinguishes: axonal vs. demyelinating; sensory vs. motor vs. mixed; mononeuropathy vs. polyneuropathy
  • Key finding in axonal neuropathy: low-amplitude SNAPs with preserved conduction velocities
  • Key finding in demyelinating: slowed conduction velocity, prolonged latencies, conduction block
"The electrophysiologic data can confirm whether the neuropathic disorder is a mononeuropathy, multiple mononeuropathy, radiculopathy, plexopathy, or generalized polyneuropathy." - Harrison's Principles of Internal Medicine 22e, p. 3644
Limitation: NCS/EMG can be normal in pure small-fiber neuropathy (which classically causes burning pain without weakness or reflex loss). In that case:

Step 5 - Small-Fiber Neuropathy-Specific Tests

When NCS/EMG is normal but burning symptoms are prominent:
TestDetails
Skin punch biopsy (3 mm, distal leg)Measures intraepidermal nerve fiber density (IENFD); loss confirms small-fiber neuropathy. Single most useful confirmatory test.
Quantitative sensory testing (QST)Assesses thresholds for temperature and vibration
Quantitative sudomotor axon reflex test (QSART)Evaluates autonomic/sudomotor small fibers
Autonomic studiesHeart rate variability, orthostatic BP
"The diagnosis of small-fiber neuropathy is best accomplished when at least two abnormal results are present, including positive clinical findings, quantitative sensory testing, QSART, and skin biopsy." - Bradley and Daroff's Neurology in Clinical Practice

Step 6 - Additional Targeted Tests (Selective)

ScenarioTest
Suspected toxic neuropathyHeavy metal screen (lead, arsenic, mercury, thallium), 24-hr urine
Porphyria (episodic, psychiatric features)Urine porphyrins, ALA, PBG
Paraneoplastic neuropathyAnti-Hu, anti-Yo, anti-CV2, CT chest/abdomen/pelvis
SarcoidosisACE level, chest X-ray / CT
Celiac diseaseAnti-tissue transglutaminase IgA, IgA level
Fabry disease (young male, acral burning, family history)Alpha-galactosidase A activity in leukocytes

Summary Algorithm

Burning feet
    |
    ├── History + Exam
    |
    ├── First-line labs: glucose/HbA1c, CBC, CMP, B12, TSH, SPEP, ESR
    |
    ├── NCS/EMG
    |       |
    |       ├── Abnormal → characterize neuropathy, guide further workup
    |       └── Normal → consider small-fiber neuropathy
    |
    └── If small-fiber suspected → skin biopsy (IENFD) + QST + QSART
The most common final diagnoses are diabetic neuropathy, prediabetic neuropathy, B12 deficiency, cryptogenic sensory neuropathy, and small-fiber neuropathy. A systematic screen catches the treatable causes early.
Sources: Goldman-Cecil Medicine (International Ed.), Harrison's Principles of Internal Medicine 22e, Bradley and Daroff's Neurology in Clinical Practice, Adams and Victor's Principles of Neurology 12e

Ok

Got it! Let me know if you have any follow-up questions or want to explore a specific aspect further - like interpreting results, management options, or a different clinical scenario.
This is a shared conversation. Sign in to Orris to start your own chat.