The most common cause of burning in the feet is neuropathy. Neuropathy occurs when damaged nerve fibers misfire or become overactive. When this happens, the damaged nerves send out signals to the brain to tell it that there is pain present, even when there is no injury or wound and, as a result, burning is experienced, according to WebMD.
The most common reasons that neuropathy occurs are alcohol abuse or as a result of diabetes. Still, there are other conditions that can cause neuropathy in the feet, including chronic kidney disease, low thyroid hormone levels, HIV/AIDs, small fiber neuropathy, vitamin deficiency (especially vitamin B12 and B6), Lyme disease, hypertension, fluid retention and edema, sarcoidosis, Guillain-Barre syndrome, vasculitis and metal poisoning. It can also occur as a side effect of various drugs, according to WebMD.
Most diagnoses of burning feet are fairly straightforward and can be made without further testing. However, in cases where no apparent cause for neuropathy can be determined, tests to diagnose the condition may include muscle functioning tests using electromyography and nerve conduction studies. Tests of urine, blood and spinal fluid may also be taken. In rare cases, doctors may order nerve biopsy to get a better look at the nerve tissue to make a definitive diagnosis and find the cause of burning feet, as noted by WebMD.