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Diagnosis and Testing for Chronic Fatigue Syndrome & Myalgic Encephalomyelitis


By Erica Verrillo*

Taking a careful history is essential for making a diagnosis, as is comparing the patient’s symptoms with a case definition.

Currently, there are several case definitions for ME/CFS. Physicians who are not ME/CFS specialists rely on the CDC case definition (also known as the Fukuda definition) to make a diagnosis. Because the Fukuda definition is very broad, it often leads to misdiagnosis (De Becker, et al, Jason et al.). As a consequence, ME/CFS specialists prefer to use the more accurate Canadian Consensus Criteria (CCC), or the International Consensus Criteria (ICC) (Carruthers et al.).

You may be asked to fill out a questionnaire, such as the DePaul Symptom Questionnaire, prior to your visit, to help the physician assess the frequency and severity of your symptoms (Jason et al.)

In addition, the physician should take into account the type of onset (acute or insidious), triggering mechanisms (exposure to chemicals, viral infection, physical trauma), and any other factors that might influence the severity or persistence of the illness. Symptoms that develop quickly after an initial trigger are indicative of Chronic Fatigue Syndrome & ME. In adolescents, the initial trigger is frequently mononucleosis.

Most specialists question their patients carefully about the type of symptoms they are experiencing. ME/CFS is a syndrome, which means that multiple symptoms are present. Many of these symptoms are reflective of an autonomic nervous system disorder; others are indicative of a persistent viral infection. What is important to the doctor is not necessarily that you have all of the symptoms, or even a certain percentage, but that they cover a spectrum. The symptoms most doctors consider as particularly significant are the persistent loss of energy not relieved by rest, a worsening of symptoms after mild exertion (post-exertional malaise), pain, sleep disorders, and cognitive problems. Other symptoms can occur in an astonishing array.

Even if the patient does not have all of the symptoms, it is unlikely that a doctor will make diagnosis based strictly on fatigue. Fatigue is one of the primary symptoms of depression. However, unlike patients with ME/CFS, those with depression feel better after exercise. Any doctor familiar with Chronic Fatigue Syndrome & ME will ask the question, “How do you feel after exercise?” to rule out depression.

Conscientious physicians should order all the necessary tests to rule out illnesses that produce similar symptoms, as these may be treated with existing protocols. A significant percentage of patients who have rare or hard-to-detect diseases, such as Behçet’s Disease, rare forms of leukemia, early MS, and empty sella (shrunken pituitary) have been erroneously diagnosed with chronic fatigue syndrome, because they initially present with fatigue. It is important for patients to mention symptoms other than fatigue in the initial interview to avoid misdiagnosis.

Any competent physician will also perform a physical exam. While ME/CFS is often called an “invisible illness,” there are some distinctive features that are apparent during a routine examination.

Initial Office Observations

  • Blood pressure: usually low (orthostatic hypotension)
  • Temperature: low (97° F) or slightly elevated (<100° F) or, more commonly, both over the course of a day (excessive diurnal variation)
  • Heartbeat: tachycardia (hard to detect in an office visit; Holter monitor is more efficient)
  • Throat: irritated, crimson crescents
  • Lymph nodes: tenderness in nodes of groin and neck, particularly on left side
  • Pallor: usually present
  • Positive Romberg test (tandem stance)
  • Stiff, slow gait
  • Nystagmus (involuntary eye movements)
  • Photophobia (light sensitivity)
  • Hyperreflexia (increased reflex reactions)


Common Findings on Routine Screening Tests

Physicians usually order routine screening tests, such as a complete blood count (CBC) with differential, a urinalysis, and liver function tests, as part of their initial examination. While these tests are useful to eliminate other possible diagnoses, there are also a few abnormalities that are typical of people with ME/CFS.

  • Decreased number of white blood cells (leukopenia), also increased number of white blood cells
  • Abnormal red blood cell membranes, elevated MCV (large red blood cells)
  • Low concentrations of zinc and magnesium
  • Low uric acid concentration (<3.5 mg/dl)
  • Total cholesterol concentration slightly elevated
  • Decreased potassium and sodium
  • Sedimentation rate: Low (<5 mm/hr); sometimes brief periods of elevated rate (>20 mm/hr)
  • Urinalysis: alkaline; mucus or blood, or both, without bacterial infection
  • Positive ANA, speckled pattern
  • Liver function tests: mildly elevated AST (SGOT) and ALT (SGPT)


What Tests Are Recommended for ME/CFS?

When a patient presents with debilitating fatigue as a primary symptom, physicians must perform a battery of tests to rule out other illnesses that produce chronic fatigue, including leukemia, MS, kidney disease, brain injury, liver disease, thyroid disease, infections such as Lyme, and autoimmune diseases.

In most instances, exclusionary tests are not expensive or difficult to perform. Depending on the symptoms, the physician may wish to rule out ongoing Lyme disease, lupus, rheumatoid arthritis or other autoimmune disorders, parasitic infections, heart disease, specific neurological disorders such as multiple sclerosis, endocrine disorders such as hypothyroidism, and systemic infections and inflammatory conditions (as indicated by a high erythrocyte sedimentation rate). In general, patients with ME/CFS test negative for other conditions. However, as many physicians have noted, nothing prevents a person from having two conditions simultaneously or developing one after the other. Thus a positive test result does not necessarily rule out a diagnosis of ME/CFS.

Autoimmunity: negative for lupus, rheumatoid arthritis, Hashimoto’s disease. Note: Patients sometimes test positive on initial screening but not on more specific tests.

Endocrine system: negative for Addison’s disease, Cushing’s disease, hypothyroidism, diabetes mellitus. Note: Although some patients with ME/CFS with enlarged thyroid gland test negative on standard tests, more refined tests may reveal secondary thyroid deficiencies. Many patients also develop co-morbidities such as Hashimoto’s disease and diabetes.

Heart: negative for mitral valve prolapse. Note: Test is warranted if the patient reports tachycardia. Tests sometimes reveal elevated transaminase concentrations and angiotensin-converting enzyme.

Liver: negative for hepatitis

Nervous system: negative for multiple sclerosis (MS). Note: Test is warranted if patient shows severe neurological, cognitive, and muscle dysfunction. Although some patients with ME/CFS may test negative for MS, more specific testing (brain function) may reveal abnormalities.

Bacterial: negative for tuberculosis, brucellosis, Lyme disease

Cancer: negative for lymphoma and leukemia

Parasites: negative for toxoplasmosis, giardiasis, amoebiasis. Note: Patients with ME/CFS can have multiple parasitic infections as part of a prodromal illness.

* Erica Verrillo is ProHealth’s expert editor for the ME/CFS HealthWatch and Natural Wellness newsletters. She is the author of Chronic Fatigue Syndrome: A Treatment Guide, 2nd Edition, available as an electronic book on Amazon,Barnes & Noble, Kobo and Payhip (PDF file). Her website,CFSTreatmentGuide.com, provides practical resources for patients with ME/CFS. She also writes a blog, Onward Through the Fog, with up-to-date news and information about the illness, as well as the full text of CFS: A Treatment Guide, 1st Edition (available in translation).

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