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