WASHINGTON (HealthDay News) -- A spinal fluid protein may prove useful in identifying people with the earliest stages of multiple sclerosis (MS), say researchers at Johns Hopkins University in Baltimore.

Currently, MS cannot be diagnosed with a simple blood sample or any other type of test.

"There is the possibility now that the protein we identified, 12.5kDa cystatin, can be used to diagnose MS, perhaps in its earliest stages, and also to monitor treatment by measuring its levels in cerebrospinal fluid," study author Dr. Avindra Nath, a professor in the department of neurology at Johns Hopkins University School of Medicine, said in a prepared statement.

Nath and his colleagues analyzed samples of cerebrospinal fluid from 29 people with MS or pre-MS symptoms, and found 12.5kDa present in about two-thirds of the patients.

The Hopkins scientists showed that 12.5kDa is a breakdown product of a larger protein called cystatin C, which blocks the activity of some enzymes, including cathepsin B. This enzyme has been linked to the demyelination -- nerve sheath destruction -- that occurs in people with MS.

About 10,000 Americans, mostly women, are diagnosed with MS each year. The disease causes muscle weakness, numbness, loss of muscle coordination, and problems with speech, vision and bladder control. In people with MS, the immune system destroys myelin, the covering of the nerves that helps transmit signals.