Index
Diagnostic Criteria For CFS
Diagnosing CFS

The following information was taken from the CFS Home Page

Diagnosing CFS

Q: Can CFS be diagnosed by laboratory tests?

A: No diagnostic test exists for CFS. Currently, laboratory tests are useful solely to rule out other causes of fatigue. The same is true of serologic tests for certain viruses. Numerous scientific reports have documented immunologic differences between groups of CFS patients and healthy controls, but differences are not observed consistently, and test results between individual patients and controls overlap considerably. In other words, the test values for a randomly chosen CFS patient and for a randomly chosen healthy person may both fall into the normal range for any of these tests.

Q: How is CFS diagnosed?

A: CFS is currently diagnosed by a history of illness suggestive of CFS and through the systematic exclusion of other possible causes. A patient must first have profound fatigue and other characteristic symptoms for a minimum of 6 months. To complete the diagnosis, a physician must rule out the many clinically defined (and often treatable) causes of chronic fatigue by using a panel of routine diagnostic tests. Consult Screening tests for common exclusionary conditions for specific examples of laboratory tests used to exclude other illnesses that may cause severe fatigue.

Q: Are there CFS specialists who are more qualified than physicians in general practice to diagnose this illness?

A: As with any illness, some physicians are more familiar with CFS than others, but any licensed physician should be able to diagnose CFS. Persons who suspect they might have CFS should seek a doctor with whom they have a comfortable rapport, and who has knowledge of or is open to learning about CFS. Call the nearest university-based medical center if you have difficulty locating a physician who is familiar with the syndrome.

Q: Can CFS be diagnosed by using extremely sensitive molecular tests to demonstrate the presence of retrovirus-like DNA sequences?

A: No. One published report has been erroneously interpreted to indicate that CFS can be diagnosed by using the polymerase chain reaction method to detect human T-cell lymphotrophic virus type II (HTLV-II)-like DNA sequences in the lymphocytes of patients. However, more recent studies do not support this view. As such, this expensive research test is not useful in the diagnosis of CFS (see Possible Causes of CFS, in this section).

Q: Should diagnostic imaging techniques, such as MRI, PET scan, and SPECT scan, be used in the diagnosis of CFS?

A: Several reports in the peer-reviewed clinical literature have described CFS patients with recognizable abnormalities seen in MRI or SPECT scans of the brain. However, these preliminary reports have not been confirmed by definitive follow-up studies and did not identify abnormalities in all CFS patients. Since the importance of these early reports is not known, these costly procedures are not appropriate for the clinical diagnosis of CFS.

Q: CFS patients have been shown to have increased antibody levels (i.e., elevated titers) to various infectious agents, including EBV, cytomegalovirus, HHV-6, rubella, enteroviruses, and Borrelia . Does this observation indicate that CFS can be triggered by the reactivation of latent infections?

A: Some viruses, most notably the herpesviruses, can establish a state of prolonged dormancy, known as a latent infection, within their host. Such viruses normally reactivate periodically and consequently restimulate the immune system. Published studies have reported elevated titers to a number of these agents among CFS patients compared with controls. However, test values between individual patients and controls broadly overlap, indicating that such tests cannot be used to diagnose CFS. Early studies concluded that there was an association between high levels of serum antibody to EBV (which is known to cause fatigue) and CFS. However, more recent studies have shown that elevated EBV titers are not correlated with CFS. Rubella, enteroviruses, and Borrelia cannot produce a latent infection, but they can persist for prolonged periods in an infected person. Finally, because persons within a given population exhibit a broad range of titers to viruses that establish latent infections, "elevated titer" is difficult to define. As such, serolgic assays for agents that cause latent or persistent infections have no value in the diagnosis of CFS.

Q: Can CFS be diagnosed on the basis of an abnormal upright tilt table test?

A: A recent study of chronic fatigue patients at Johns Hopkins University revealed that 22 of 23 CFS patients exhibited an abnormal response (neurally mediated low blood pressure) to a three-stage tilt table test. In contrast, only 4 of 14 controls had abnormal responses. The same research group had earlier reported that neurally mediated low blood pressure could lead to the development of prolonged fatigue. Sixteen of 21 patients in the tilt table study responded to treatment with electrolyte regulating agents or beta adrenergic blocking agents with complete recovery or improved symptoms. This intriguing study will need to be confirmed by other investigators.

Q: Can CFS be diagnosed by laboratory tests?

A: No diagnostic test exists for CFS. Currently, laboratory tests are useful solely to rule out other causes of fatigue. The same is true of serologic tests for certain viruses. Numerous scientific reports have documented immunologic differences between groups of CFS patients and healthy controls, but differences are not observed consistently, and test results between individual patients and controls overlap considerably. In other words, the test values for a randomly chosen CFS patient and for a randomly chosen healthy person may both fall into the normal range for any of these tests.

Q: How is CFS diagnosed?

A: CFS is currently diagnosed by a history of illness suggestive of CFS and through the systematic exclusion of other possible causes. A patient must first have profound fatigue and other characteristic symptoms for a minimum of 6 months. To complete the diagnosis, a physician must rule out the many clinically defined (and often treatable) causes of chronic fatigue by using a panel of routine diagnostic tests. Consult Screening tests for common exclusionary conditions for specific examples of laboratory tests used to exclude other illnesses that may cause severe fatigue.

NOTE: A brief overview of the process of diagnosing CFS, including a description of tests used to exclude other illnesses, is included in the CFS Defined section.

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