Box 4.

: Stage 3 investigation of peripheral neuropathy

• Urine—Bence-Jones protein
• Biochemistry—Oral glucose tolerance test
• Cerebrospinal fluid—Cells, protein, immunoglobulin oligoclonal bands
• Immunology—Anti-HIV antibodies, antineuronal antibodies (Hu, Yo), antigliadin antibodies, serum angiotensin converting enzyme, antiganglioside antibodies, antimyelin associated glycoprotein antibodies
• Tests for Sjögren's syndrome—Salivary flow rate, Schirmer's test, Rose Bengal test, labial gland biopsy
• Search for carcinoma, lymphoma, or solitary myeloma—Skeletal survey, pelvic ultrasonography, abdominal and chest computed tomography, mammography, or positron emission tomography
• Molecular genetic tests—Peripheral nerve myelin protein 22 gene duplication (the commonest cause of Charcot-Marie-Tooth disease type 1) or deletion (hereditary neuropathy with liability to pressure palsies), connexin 32 mutation (X linked Charcot-Marie-Tooth disease), PO gene mutation (another cause of Charcot-Marie-Tooth disease type 1), etc