Arkana Laboratories offers Epidermal Nerve Fiber Density (ENFD) Testing. ENFD testing is widely used by neurologists in the United States and Europe to evaluate for small fiber neuropathy.

epidermal nerve fiber density test for small fiber neuropathy diagnosis

Specimen Handling & Transport

It is essential that skin biopsy is immediately-fixed in the provided fixative (Zamboni’s) for evaluation (see additional instructions below).

Please only transport specimens Monday-Thursday.

Optimal results are obtained when the specimen is not fixed for more than 24 hours. Results are final within 3-5 days.

Skin Biopsy Specimen Collection

Biopsy of proximal and distal sites allows for assessment of length-dependent processes. Alternative biopsy sites are best evaluated by also submitting a punch biopsy from a similar location in the opposite non-affected limb to serve as a reference control.

Download ENFD Req Form
Distal lower leg 10.0 cm above the lateral malleolus (most common site)
Distal Thigh 7.0 cm above the knee, lateral
Proximal Thigh 20.0 cm below the anterior iliac spine, upper lateral thigh

Biopsy Handling Protocol:

  1. Clean the biopsy site with alcohol swabs and numb the area(s) with local anesthesia (for example 1% lidocaine or 1% lidocaine with epinephrine).
  2. Use provided 3.0 mm biopsy punch; rotate with light pressure to 2/3 of its depth (2 to 3 mm).
  3. Use forceps and scissors to carefully remove the biopsy specimen (do not grasp or pinch the epidermis when removing the punch biopsy as this will crush the small nerves we are measuring).
  4. Immediately place the removed biopsy into the appropriate labeled specimen vial containing Zamboni’s fixative and tightly close the lid.
  5. Label specimen containers with biopsy site and two patient identifiers (e.g. name and date of birth).


Download ENFD Protocol