Blood tests according to clinical suspicion of underlying SFN etiologies
| Etiologies associated with SFN | Diseases | Blood tests and other investigations |
|---|---|---|
| Metabolic | DM, IFG, IGT, hypertriglyceridemia, hypothyroidism | HbA1C, FG, OGTT, TFT |
| Nutritional deficiencies | - | vit B1, vit B12 |
| Infectious | HIV, HCV, HBV, Lyme disease | CRP, HIV, Borrelia burgdorferi, HBV, HCV, lumbar puncture |
| Autoimmune | Vasculitis, SLE, Sjögren’s syndrome (SS), rheumatoid arthritis, connective tissue disease, celiac disease, sarcoidosis | ESR, ANA, anti-ENA, SLE panel, ANCA, anti-transglutaminase antibody, RF, serum ACE, CXR, lumbar puncture |
| Paraneoplastic | Small cell lung cancer, solid tumors, lymphoma, myeloma, monoclonal gammopathies | Tumor markers, LDH, myeloma screen, SPE, UPE, anti-Hu and anti-CV2/CRMP-5 antibodies, lumbar puncture, whole body PET/CT |
| Neurotoxins | Metronidazole, alcohol, chemotherapeutic agents, solvents | Urine + blood toxicology, EtOH level, GGT, MCV, screen and review drug history |
| Hereditary | Fabry disease, HSAN, hATTR, Nav 1.7, Nav 1.8 and Nav 1.9 sodium channelopathies | Leukocyte alpha-galactosidase A and globotriaosylceramide (Gb3 or GL-3) levels, renal panel, urine protein, genetic testing for TTR, HSAN, SCN9A, SCN10A, SCN11A, skin/nerve/other peripheral fat pad biopsy for congo red staining |
IFG: impaired fasting glucose; IGT: impaired glucose tolerance; HbA1C: hemoglobin A1C; FG: fasting glucose; OGTT: oral glucose tolerance test; TFT: thyroid function tests; EtOH: ethanol; GGT: gamma-glutamyl transpeptidase; MCV: mean cell volume; CRP: C-reactive protein; hATTR: hereditary transthyretin amyloidosis; HIV: human immunodeficiency virus; HBV: hepatitis B virus; HCV: hepatitis C virus; SLE: systemic lupus erythematosus; ESR: erythrocyte sedimentation rate; ANA: anti-nuclear antibody; anti-ENA: ant-extractable nuclear antigens; ANCA: anti-neutrophil cytoplasmic antibody; RF: rheumatoid factor; ACE: angiotensin converting enzyme; CXR: chest X-ray; LDH: lactate dehydrogenase; SPE: serum protein electrophoresis; TTR: transthyretin, UPE: urine protein electrophoresis; HSAN: hereditary sensory autonomic neuropathy; Nav 1.7: SCN subunit 1.7; CV2/CRMP-5: CV2/collapsing response mediator protein 5; Gb3 or GL-3: globotriaosylceramide; -: information not available