title: Causes of neuropathy in patients referred as "idiopathic neuropathy".
abstract: The etiology of neuropathy was idiopathic in 20%-30% of patients despite thorough investigation, based on results from the 1980s and 1990s. Since then, new etiologies have been recognized, and skin biopsy has been used to confirm small-fiber neuropathy.
  
  
  
  The authors reviewed the charts of 373 patients with idiopathic neuropathy who were referred to a neuropathy center between 2002 and 2012.
  
  
  
  Among the 284 eligible patients, 93 (32.7%) remained idiopathic. The most common cause was impaired glucose metabolism (72 patients, 25.3%), including diabetes in 26 and prediabetes in 46. Other etiologies were chronic inflammatory demyelinating polyneuropathy (CIDP) in 57 (20%) and monoclonal gammopathy in 20 (7%), as well as toxic, Sjögren disease, celiac disease, other immune-mediated diseases, vitamin B12 deficiency, amyloidosis, vitamin B1 and B6 deficiency, vasculitis, hypothyroidism, hereditary, Lyme disease, and anti-sulfatide antibody.
  
  
  
  The major causes of undiagnosed neuropathies were impaired glucose metabolism, CIDP, and monoclonal gammopathies. Despite thorough evaluation 32.7% remained idiopathic. Muscle Nerve 53: 856-861, 2016.
authors.affiliation: Peripheral Neuropathy Center, Neurological Institute of New York, Columbia University Medical Center, 710 West 168th Street, New York, New York, 10032, USA.
authors.forename: Khosro
authors.initials: K
authors.lastname: Farhad
authors.affiliation: Peripheral Neuropathy Center, Neurological Institute of New York, Columbia University Medical Center, 710 West 168th Street, New York, New York, 10032, USA.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Traub
authors.affiliation: Peripheral Neuropathy Center, Neurological Institute of New York, Columbia University Medical Center, 710 West 168th Street, New York, New York, 10032, USA.
authors.forename: Katherine M
authors.initials: KM
authors.lastname: Ruzhansky
authors.affiliation: Peripheral Neuropathy Center, Neurological Institute of New York, Columbia University Medical Center, 710 West 168th Street, New York, New York, 10032, USA.
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Brannagan
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010265:Paraproteinemias / Q000150:complications*; D010523:Peripheral Nervous System Diseases / Q000175:diagnosis* / Q000209:etiology*; D020277:Polyradiculoneuropathy, Chronic Inflammatory Demyelinating / Q000150:complications*; D012189:Retrospective Studies; D055815:Young Adult
keywords: CIDP; MGUS; diabetes; idiopathic; neuropathy; prediabetes