Serologic testing to find the cause of small fiber neuropathy
| First-tier studies | Associated conditions |
|---|---|
| 2-hour oral glucose tolerance test, hemoglobin A1c | Diabetes, impaired glucose tolerance |
| Extractable nuclear antigen testing for Sjögren syndrome A and B antibodies | Sjögren syndrome |
| Thyroid-stimulating hormone, free T4, T3 levels | Hypothyroidism |
| Vitamin B12, methylmalonic acid, homocysteine levels | Vitamin B12 deficiency |
| Serum and urine monoclonal protein analysis | Paraproteinemia |
| Tissue transglutaminase, antigliadin antibodies | Celiac disease |
| Complete metabolic panel | Renal, hepatic impairment |
| Complete blood cell count | Hematologic abnormalities |
| Human immunodeficiency virus (HIV) and hepatitis C virus antibodies (may be second-tier tests if no risk factors) | HIV, hepatitis C |
| Fasting lipid panel | Hyperlipidemia |
| Erythrocyte sedimentation rate, C-reactive protein, antinuclear antibody | Inflammatory disease |
| Liver function tests, gamma-glutamyltransferase | Alcohol abuse |
| Second-tier studies | |
| Angiotensin-converting enzyme | Sarcoidosis |
| Thiamine (vitamin B1) | Vitamin B1 deficiency |
| Pyridoxine (vitamin B6) | Vitamin B6 deficiency |
| Copper | Copper deficiency |
| Serum and urine monoclonal protein analysis, fat pad analysis, nerve biopsy | Systemic amyloidosis |
| Paraneoplastic autoantibody panel | Paraneoplastic disease |
| Ganglionic acetylcholine receptor antibody | Autoimmune autonomic ganglionopathy |
| Genetic studies | |
| SCN9A and SCN10A genes | Hereditary small fiber neuropathy |
| GLA gene | Fabry disease |
| Transthyretin gene | Familial amyloidosis |
| ABCA1 gene | Tangier disease |