WINSTON-SALEM, N.C., Sept. 25 (UPI) -- A U.S. study suggests that an an enzyme is why some patients with kidney failure can develop a rare tightening and swelling of the skin and other organs.

Researchers at Wake Forest University Baptist Medical Center in Winston Salem, N.C., suggest a possible explanation for why some patients on kidney dialysis who are injected with a "contrast agent" during a magnetic resonance imaging develop nephrogenic systemic fibrosis, known as NSF.

The study, published in the October issue of the American Journal of Dermatopathology, found that an enzyme known as transglutaminase-2 may be involved. The enzyme is found throughout the body and is involved in blood clotting and wound healing.

The researchers, led by Dr. David C. Sane, hypothesized that gadolinium -- an agent injected into patient’s veins during some MRI procedures to help improve the visibility of internal organs during the test -- may activate the enzyme and cause NSF.

"Compared to the healthy subjects, there was a marked increase in transglutaminase-2 in the subjects with NSF," Sane said in a statement. "This suggests that activation of transglutaminase-2 can produce the syndrome."

NSF in found in about 2 percent to 4 percent of kidney patients on dialysis who are exposed to gadolinium.