Diagnostic biomarker

A diagnostic biomarker refers to a biological parameter that aids the diagnosis of a disease. It may be a laboratory, radiological, genetic, anatomical, or other finding that differentiates one disease from others. Potential diagnotic biomarkers for ME/CFS are being explored by many researchers in the field. Below is a list of some that have been considered:

Short QT interval
"Automated measurement of QTc [QT corrected] in clinical practise has potential utility as a diagnostic biomarker in CFS."

The electrocardiographic QT interval is shorter in patients with ME/CFS than those of the general population. The only exception is in those who have a rare genetic illness, Short QT syndrome. Differentiation is easy to determine because those with Short QT syndrome also have tall and peaked T waves, whereas the T waves are normal in PwME. Modern computer-based ECG machines are programed to correct the QT interval in relation to heart rate, because a number of medical conditions illicit a prolonged QT interval.

Obstacle for use: medical personnel education needed to recognize this finding on the EKG finding as indicative of ME/CFS; modern computer-based EKG machine needed

Natural killer cell function
Numerous studies of Chronic Fatigue Syndrome have found evidence of reduced natural killer cell function. Some studies have showed natural killer cell function correlates with illness severity. One study found increased differentiation in NK cells.

Obstacle for use: Specialized lab equipment not available in average laboratories; blood specimen must be tested within 48 hours of draw and must remain at between 59°-98.6°F or 15°-37°C so special considerations are needed in transporting blood specimens to specialized labs.

DePaul symptom questionnaire
The DePaul symptom questionnaire (DSQ) is a self-report assessment created by Leonard Jasonand the Chronic Fatigue Syndrome Project at DePaul University, Chicago, Illinois, USA. The "DSQ is useful for detecting and screening symptoms consistent with a CCC diagnosis in clinical practice and research. However, it is important for initial screening of self-report symptoms to be followed up by subsequent medical and psychiatric examination in order to identify possible exclusionary medical and psychiatric disorders." "A score of 20 on the post-exertional malaise subscale of the DePaul Symptom Questionnaire optimally differentiated between patients and controls."

Obstacle for use: Subsequent medical and psychiatric examination would require medical personnel educated in the diagnosis ME/CFS to confirm the DePaul symptom questionnaire scoring.

Two-day cardiopulmonary exercise testing
Two-day cardiopulmonary exercise testing or 2-day CPET is an accepted, reliable test for post-exertional malaise (PEM), one of the cardinal symptoms that distinguishes between individuals with and without ME/CFS.

Obstacle for use: The 2-day CPET "carries substantial risk for these patients as it may worsen their condition." A single day CPET is a common test used as a cardiac stress test and therefore the equipment is widely available at medical centers, however, medical personnel would need to be educated on how to interpret a 2-day CPET test for ME/CFS diagnosis.

Brain imaging
Using advanced brain imaging, Michael Zeineh, et.al., found that there was right arcuate fasciculus (FA) abnormality in CFS patients. "Bilateral white matter atrophy is present in CFS...Right hemispheric increased FA may reflect degeneration of crossing fibers or strengthening of short-range fibers. Right anterior arcuate FA may serve as a biomarker for CFS."

Obstacle for use: The specialized radiological equipment needed for this test is usually only available in facilities engaged in research.

Chronic cell danger response state
Robert Naviaux, et al, at the University of California, San Diego School of Medicine reported in 2016 "that targeted, broad-spectrum metabolomics of plasma not only revealed a characteristic chemical signature but also revealed an unexpected underlying biology."

Obstacle for use: The specialized labortory equipment needed for this test is usually only available in facilities engaged in research.