number of tests, some of which are offered commercially, have no demonstrated value for the diagnosis of CFS. These tests should not be performed unless required for diagnosis of a suspected exclusionary condition (e.g., MRI to rule out suspected multiple sclerosis) or unless they are part of a scientific study. In the latter case, written informed consent of the patient is required. No diagnostic tests for infectious agents, such as Epstein-Barr virus, enteroviruses, retroviruses, human herpesvirus 6, Candida albicans, and Mycoplasma incognita, are diagnostic for CFS and as such should not be used (except to identify an illness that would exclude a CFS diagnosis, such as mononucleosis). In addition, no immunologic tests, including cell profiling tests such as measurements of natural killer cell (NK) number or function, cytokine tests (e.g., interleukin-1, interleukin-6, or interferon), or cell marker tests (e.g., CD25 or CD16), have ever been shown to have value for diagnosing CFS. Other tests that must be regarded as experimental for making the diagnosis of CFS include the tilt table test for NMH, and imaging techniques such as MRI, PET-scan, or SPECT-scan. Reports of a pathway marker for CFS as well as a urine marker for CFS are undergoing further study; however, neither is considered useful for diagnosis at this time.
