Is There A Diagnostic Blood Test to Tell if I Have Fibromyalgia AND Is it a Good Test?

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Is there a blood test for fibromyalgia

No, unfortunately there is not a conclusive blood test to diagnose you with fibromyalgia.

The FM/a test is expensive (around $1000 USD and its specificity and sensitivity is low (below 70 %) and researchers question if it is even that high. FM/a test is a test for fibromyalgia that has been widely advertised and advanced in the United States. However, this test has not been approved in Canada because of the low sensitivity and specificity, which makes this test very unreliable.

Here is what all that means:

A diagnosis is made from a combination of the symptoms the person experiences, a physical examination which shows signs related to the disease and diagnostic tests (blood tests, X-Rays, scans) that confirm or exclude possible diagnoses.

Is it a Good Test or Not Good Test?

In figuring out if a test is a reliable good test one must look at the test’s Sensitivity and Specificity.

Sensitivity of a Blood Test

Sensitivity refers to how accurate the test is at truly diagnosing people who have the disease. E.g.. If a person has the disease what is the likelihood they will test positive.

100% sensitivity = 100% of people who have the disease test positive (good)

70% sensitivity = 70% of people who have the disease test positive, and 30% of the people who have the disease test negative (not good)

Sensitivity should be as close to 100 % as possible which means that everyone who does not have the disease tests negative.

Specificity of a Blood Test

Specificity refers to how accurate the test is at truly telling if a healthy person is healthy according to the test. E.g.. If a person does not have the disease they should not test positive (referred to as a “false positive”)

100% specificity = 100% of people without the disease will test negative (good). There are no false positives. E.g.. No healthy people test positive for a disease they do not have.

70% specificity = 70% of people without the disease test negative and 30% of healthy people test positive for a disease they do not have (not good)

Specificity should be in the 90 – 100 % range and the closer to 100 % the better. Specificity is important because this means that everyone who has the disease tests positive.

Conclusion

Most tests are not 100% Sensitive and 100% Specific. But, it is important to assess whether a diagnostic test will add value in deciding whether a person has a specific diagnosis.

DISCLAIMER STATEMENT: Please note that the contents of this article is for information and personal education purposes only. It is not intended to replace professional, medical, or healthcare advice. We encourage users to always consult with your healthcare provider regarding your medical care, treatment, and wellness.

by FAC Research Committee April, 2024

Sources: Cochrane UK

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