Is there a blood test for CRPS?

This is a question I hear quite frequently, and given the potentially devastating effect of CRPS, it seems surprising that there is not yet one definitive diagnostic test. But is that set to change?

IASP criteria for CRPS

Currently, a CRPS diagnosis relies on the International Association for the Study of Pain (IASP) clinical diagnostic criteria (as amended), often referred to as the Budapest Criteria. CRPS largely remains a diagnosis of exclusion. Although clinicians sometimes refer people for medical tests, including blood tests and radiography, their purpose is to exclude other diseases rather than being diagnostic of CRPS.

Following diagnosis, there should be a referral to a multidisciplinary team for treatment. Typically, the treatment team comprises pain physicians, psychiatrists, psychologists, physiotherapists, and occupational therapists. Generally, the earlier the referral to the multidisciplinary team, the better the patient’s prospects. Unfortunately, however, in many cases, referral occurs after the condition is well-established.

Biomarker for CRPS

The diagnostic and therapeutic challenges presented by CRPS highlight the need for a simple, objective diagnostic test. Indeed, researchers in the field of chronic pain have been studying a variety of diagnostic biomarkers, and some of the results are quietly encouraging.

A biomarker is a molecule found in blood or elsewhere in the body that is a sign of an abnormal (or normal) body process or a disease or condition.

In one study, entitled Novel immune biomarkers in complex regional pain syndrome, published in the Journal of Immunobiology, detecting various inflammatory biomarkers allowed researchers to distinguish between control subjects and people with established CRPS. And more recently, the American Society for Surgery of the Hand has published an interesting article reviewing the development of diagnostic biomarkers for several chronic pain conditions affecting the upper limb, including CRPS.

Although a simple blood or other diagnostic test for CRPS and other pain conditions is still some way off, studies have been encouraging. Such a test is long overdue, and with a widespread clinical need, I hope the further research required proves attractive to the biosciences industry.