A nerve conduction study is generally used as the initial diagnostic step. However, the nerve conduction study is often normal in patients with an early neuropathy or a neuropathy that only involves the small fiber nerves. Quantitative sweat test and skin biopsy with measurement of intraepithelial nerve fiber density are other modalities that can be used in an appropriate setting.
Neuropathy is a common disease and neuropathy associated with celiac disease is probably a rare entity. Therefore, positive serology to celiac disease-related antigens (e.g. gliadin) in a patient with neuropathy does not automatically prove that celiac disease is the cause of the neuropathy. Importantly, a workup has to be done to unravel other more common causes of neuropathy. Specifically, patients should be assessed for diabetes, nutritional deficiencies and other autoimmune diseases. Also, the existence of celiac disease should be proven with an intestinal biopsy if the serologic tests are positive. In patients with a rapidly progressive neuropathy, a nerve biopsy has to be considered to assess for other treatable causes of neuropathy (like inflammation in the nerves or blood vessels).