Investigation

• there are no validated laboratory or other tests to confirm chronic fatigue syndrome (CFS)

If ME (myalgic encephalitis)/CFS (chronic fatigue syndrome) is suspected, carry out (2):

• a medical assessment (including symptoms and history, comorbidities, overall physical and mental health)
• a physical examination
• an assessment of the impact of symptoms on psychological and social wellbeing
• investigations to exclude other diagnoses, for example (but not limited to):
  • urinalysis for protein, blood and glucose
  • full blood count
  • urea and electrolytes
  • liver function
  • thyroid function
  • erythrocyte sedimentation rate or plasma viscosity
  • C-reactive protein
  • calcium and phosphate
  • HbA1c
  • serum ferritin
  • coeliac screening
  • creatine kinase

Use clinical judgement to decide on additional investigations to exclude other diagnoses (for example, vitamin D, vitamin B12 and folate levels; serological tests if there is a history of infection; and 9am cortisol for adrenal insufficiency)

Be aware that the following symptoms may also be associated with, but are not exclusive to, ME/CFS:

• orthostatic intolerance and autonomic dysfunction, including dizziness, palpitations, fainting, nausea on standing or sitting upright from a reclining position
• temperature hypersensitivity resulting in profuse sweating, chills, hot flushes, or feeling very cold
• neuromuscular symptoms, including twitching and myoclonic jerks
• flu-like symptoms, including sore throat, tender glands, nausea, chills or muscle aches
• intolerance to alcohol, or to certain foods and chemicals
• heightened sensory sensitivities, including to light, sound, touch, taste and smell
• pain, including pain on touch, myalgia, headaches, eye pain, abdominal pain or joint pain without acute redness, swelling or effusion.

Primary healthcare professionals should consider seeking advice from an appropriate specialist if there is uncertainty about interpreting signs and symptoms and whether an early referral is needed. For children and young people, consider seeking advice from a paediatrician.

Previous NICE guidance stated that some symptoms may require further tests e.g. EMG, EEG, ECG, exclusion of inflammatory bowel disease (3)

Notes:

• previous NICE guidance stated that serological testing should not be carried out unless the history is indicative of an infection. Depending on the history, tests for the following infections may be appropriate (3):
  • chronic bacterial infections, such as borreliosis
  • chronic viral infections, such as HIV or hepatitis B or C
  • acute viral infections, such as infectious mononucleosis (use heterophile antibody tests)
  • latent infections, such as toxoplasmosis, Epstein-Barr virus or cytomegalovirus

Reference:

1. Prescribers' Journal (2000), 40 (2), 99-106.
2. NICE (October 2021). Myalgic encephalomyelitis (or encephalopathy)/chronic fatigue syndrome: diagnosis and management
3. NICE (August 2007).Chronic fatigue syndrome/ myalgic encephalomyelitis (or encephalopathy) Chronic fatigue syndrome/myalgic encephalomyelitis (or encephalopathy): diagnosis and management of CFS/ME in adults and children