Patients with Chronic Fatigue Syndrome (CFS) have severe, unexplained fatigue that is not relieved by rest, causes disability, and has a clearly defined onset.  To be considered as “chronic” it must be persistent or relapsing for at least six consecutive months.

The above description is one of the two criteria for diagnosis of CFS as defined by the Centers for Disease Control in the USA..  The other criteria is four or more of the following symptoms: impaired memory or concentration problems, tender cervical or axillary lymph nodes, sore throat, muscle pain, multi-joint pain (but not arthritis), new onset headaches (tension-type or migraine), unrefreshing sleep, and post-exertion malaise.

There may be confusion between CFS and FMS.   Like FMS there are no specific tests for confirming the diagnosis of CFS.  However, the following investigations may be useful to identify conditions that mimic CFS:

ESR (Sedimentation Rate):  Used to reveal an unrecognized inflammatory condition.

Hematology Profile: Used to rule out anemia or conditions of the white blood cells.

TSH: Used to rule out thyroid disease that is causing fatigue and muscle pain.

ANA: To rule out Lupus Erythematosus that has many features similar to Fibromyalgia.

RA: The Rheumatoid Factor test to rule out Rheumatoid arthritis.

CK (Creatine Kinase): A muscle enzyme used to rule out a muscle inflammatory condition such as polymyositis.

Other tests that depend upon associated symptoms.

References:

The Fibromyagia Network  www.fmnetnews.com