Diabetic Polyneuropathy: Test and Diagnosis

1st order laboratory parameters – obligatory laboratory tests.

  • Small blood count
  • Differential blood count [eosinophilia? Macrocytic anemia? MCV elevation in alcohol abuse/alcohol dependence?]
  • Inflammatory parameters – CRP (C-reactive protein) or ESR (erythrocyte sedimentation rate).
  • Urine status (rapid test for: pH, leukocytes, nitrite, protein, glucose, ketone, blood), sediment, if necessary urine culture (pathogen detection and resistogram, that is, testing of suitable antibiotics for sensitivity / resistance), albumin (microalbuminuria?).
  • Fasting glucose (fasting blood glucose).
  • HbA1c (long-term blood glucose value)
  • Thyroid parameters – TSH
  • Liver parameters – alanine aminotransferase (ALT, GPT), aspartate aminotransferase (AST, GOT), glutamate dehydrogenase (GLDH) and gamma-glutamyl transferase (gamma-GT, GGT).
  • Renal parameters – urea, creatinine, creatinine clearance.

Laboratory parameters 2nd order – depending on the results of the history, physical examination, etc. – for differential diagnosis of polyneuropathy (PNP).

  • Serum protein electrophoresis
  • Immunoglobulin (oligoclonal bands) [monoclonal gammopathy?]
  • Bence Jones protein (urine).
  • ANA, pANCA, cANCA, dsDNA, auto-Ak against vascular endothelium (AECA), SS-A (Ro), SS-B (La), snRNP, cryoglobulins – suspected vasculitis [see below vasculitides (inflammation of blood vessels triggered by immune reactivity)/laboratory diagnostics].
  • Infectious serological examinations
    • Borrelia serology [see below Borrelia/lab diagnostics].
    • Advanced examinations: Cytomegaly, TPHA (Treponema pallidum hamagglutination assay), HIV, hepatitis B and C.
  • Carbodeficient transferrin (CDT) ↑ (in chronic alcoholism; positive with consumption of one bottle of wine or three bottles of beer per day)* .
  • Vitamin status – vitamin B1, vitamin B6 and vitamin B12.
  • Intoxication parameters – arsenic, lead, mercury, thallium.
  • CSF puncture (collection of cerebrospinal fluid by puncture of the spinal canal) for CSF diagnosis (cell count, CSF cytology, proteins and immunoglobulins (CSF protein profile), oligoclonal bands, Borrelia AK).
  • Porphyrins in urine
  • Molecular genetic testing (PMP22 gene; most common cause: duplication at PMP22 gene on chromosome 17) – Indications:
    • Positive family history for neuropathies.
    • Suspected hereditary motor-sensitive neuropathy type I (HMSN I) or from English “Hereditary Neuropathy with liability to Pressure Palsies” (HNPP)).

* With abstinence, the values normalize within 10-14 days.