Cause			Type of neuropathy	Comments	Laboratory tests
Diseases
Acquired immunodeficiency syndrome			A	Mainly sensory	Human immunodeficiency virus test
Carcinoma (paraneoplastic syndrome)			A	Usually sensory	Paraneoplastic panel (anti-Hu, anti-Yo, anti-Ri, anti-Tr, anti-Ma, and anti-CV2 antibodies)
Chronic liver disease			M	Mainly demyelinating, especially in viral hepatitis	Hepatic transaminase, bilirubin, albumin, and alkaline phosphatase levels
Critical illness neuropathy			A	Usually acute or subacute	No specific laboratory test
Diabetes mellitus			M	Chronic; axonal may predominate	Fasting blood glucose level, glucose tolerance test, A1C level
End-stage renal disease			A	—	Serum creatinine and blood urea nitrogen levels
Hypothyroidism			A	Usually acute or subacute, but can be chronic	Thyroid-stimulating hormone level
Leprosy			A	Usually sensory	Phenolic glycolipid-1 antibody, skin biopsy
Lyme disease			A	—	Lyme titers
Lymphoma			M	Mainly axonal	CBC, imaging
Monoclonal gammopathy				Usually chronic	Urine and serum protein electrophoresis with immunofixation
	Amyloidosis		A	Usually sensory
	Multiple myeloma		M	Axonal damage predominates after treatment
	Plasmacytoma (osteosclerotic myeloma)		D	May have some axonal damage
	Monoclonal gammopathy of undetermined significance
		IgM	D	Most common; may have some axonal damage
		IgG or IgA	M	Demyelinating features often predominate
Porphyria			A	Acute	Porphyrin titers
Syphilis			A	—	Rapid plasma reagin, VDRL, cerebrospinal fluid analysis
Vitamin B6 deficiency			A	Sensory more than motor	Vitamin B6 level
Vitamin B12 deficiency			A	Peripheral neuropathy is intermixed with upper motor neuron signs	CBC; vitamin B12 and homocysteine levels; methylmalonic acid test
Drugs*
Amiodarone (Cordarone)			M	Mainly axonal with sensorimotor	No specific tests
Chloroquine (Aralen)			D	May have some axonal damage
Digoxin			A	Mainly sensory
Heroin			A	Sensorimotor
Hydralazine			A	Mainly sensory
Isoniazid			A	Mainly sensory
Lithium			A	Sensorimotor
Metronidazole (Flagyl)			A	Mainly sensory
Misoprostol (Cytotec)			A	Motor
Nitrofurantoin (Furadantin)			A	Sensorimotor
Phenytoin (Dilantin)			A	Mainly sensory
Procainamide (Pronestyl)			D	May have some axonal damage
Statins			A	Mainly sensory
Vincristine (Oncovin)			A	Sensorimotor
Vitamin B6 excess			A	Mainly sensory
Genetic disorders†
Charcot-Marie-Tooth disease					Genetic testing
	Type 1		D	Also called HMSN-I
	Type 2		A	Also called HMSN-II
Metachromatic leukodystrophy			D	—
Neuropathy with liability to pressure palsies			D	—
Refsum disease			D	Also called HMSN-IV
Toxins*
Diphtheria toxin			D	Acute presentation	Histopathology
Ethanol (alcohol)			A	Sensorimotor	No specific or practical laboratory test
Heavy metals (e.g., arsenic, lead, mercury, gold)			A	Lead and mercury mainly cause motor neuropathy	24-hour urine collection for heavy metal titers
				Arsenic causes sensorimotor neuropathy
				Gold may cause some demyelination
Organophosphates			A	Sensorimotor	No specific or practical laboratory test
Tetanus			A	Motor; acute presentation	No specific or practical laboratory test
Tic paralysis			A	Motor; acute presentation	No specific or practical laboratory test
Other causes
Idiopathic polyneuropathy			A	Diagnosis of exclusion; usually chronic	No laboratory test