What investigations should be considered to rule out other conditions in a patient suspected of having ME/CFS?

When myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is suspected, investigations should be carried out to exclude other diagnoses ¹. These investigations include, but are not limited to:

• Urinalysis for protein, blood, and glucose ¹
• Full blood count ¹
• Urea and electrolytes ¹
• Liver function tests ¹
• Thyroid function tests ¹
• Erythrocyte sedimentation rate or plasma viscosity ¹
• C-reactive protein ¹
• Calcium and phosphate levels ¹
• HbA1c ¹
• Serum ferritin ¹
• Coeliac screening ¹
• Creatine kinase ¹

Clinical judgment should be used to decide on additional investigations to exclude other diagnoses ¹. Examples of such additional investigations include vitamin D, vitamin B12, and folate levels; serological tests if there is a history of infection; and 9am cortisol for adrenal insufficiency ¹. It is important to continue with any assessments needed to exclude or identify other conditions when ME/CFS is suspected ¹.