How to interpret the RNase L cleavage assay?
The value printed in the normal or abnormal column of the report is the ratio of the relative amounts of two forms of RNase L (Ribonuclease L, a protein in a subpopulation of the white blood cells that helps to defend the body against viruses): the small (LMW), abnormal form over the large (HMW), normal form; multiplied by ten ({LMW/HMW}x10). This number reflects the ratio.
The more of the abnormal form (and thus less of the normal form) present, the higher this value. As indicated on the report, increased levels of the LMW (Low Molecular Weight) form of the RNase L have been noted in a subset of patients with Chronic Fatigue Syndrome (reported by Prof. Suhadolnik of Temple University Medical School in Philadelphia and collaborators, in the 1997 Vol.17 of the ‘Journal of Interferon & Cytokine Research’).
We consider a value of less than 0.5 to be within the normal range. Values of higher than 0.5 support the clinical diagnosis of Chronic Fatigue Syndrome. However, the result of the RNase L-test should not be seen separately from the patient’s clinical status: to reach the diagnosis, a whole range of other criteria should be fulfilled. Interpretation must always be done by a healthcare professional.
What does "37kDa" stand for?
37kDa is the molecular weight of the protein that is measured: it stands for 37 kilo Dalton. It refers to the LMW (Low Molecular Weight) RNase L Protein that is present in the white blood cells.
Is there a re-fund by the Belgian R.I.Z.I.V.?
RNase L cleavage is a "research-only" test, not recognized as a clinical test by the R.I.Z.I.V.
Private health insurance companies might or might not provide refunds. It is up to the patient to inquire about this. The invoice is proof that the test has been done.
If the result is "Negative", could I be denied disability benefits?
While it is possible that a "Positive" result might help your case to claim disability, it is important to realize that at this time neither the Social Security Administration nor most private insurance companies recognize any laboratory test as proof of having CFS.
What is the significance of a "Positive" test?
A "Positive" result in the RNase L Protein Assay indicates an abnormally high level of the low molecular weight RNase L present in the blood cells. Recently published data indicate that the presence of this marker, in conjunction with fulfilling the symptomatic criteria, correlates strongly with a diagnosis of CFS.
How can I get the RNase L cleavage determination done?
There are specific actions to be taken in order to be able to perform the test adequately. The blood should be drawn in special tubes (containing the appropriate anti-coagulants) and arrive in our laboratories within six hours after drawing.
Belgian patients can ask their physician to contact us for arrangements.
Physicians in other countries should contact a laboratory that can isolate PBMCs (Peripheral Blood Mononuclear Cells) and ship these to R.E.D. Laboratories on dry ice. For more information regarding these laboratories, please contact us.
Is the RNase L Protein Assay test safe?
The test requires that a sample of your blood be taken by a physician or other qualified healthcare practitioner. The risk is no greater that any other routine blood test.