Citrulline: a potentially simple quantitative marker of intestinal epithelial damage following myeloablative therapy.

We noted a significant decline in the serum concentrations of citrulline of 32 haematopoietic stem cell transplant recipients following intensive myeloablative therapy during the first 3 weeks after transplantation when patients have oral mucositis, a markedly disturbed gut integrity (L/R ratio) and are most at risk of infection and other severe complications. Closer inspection of the citrulline concentrations of 12 patients confirmed that the decline did indeed correspond to the onset of oral mucositis and altered gut integrity. Since serum citrulline is a reliable biochemical marker of small bowel enterocyte mass in humans with villous-atrophy-associated diseases, it may prove a useful marker for intestinal mucosal damage induced by chemotherapy, allowing the relationship between gut mucosal damage and post-transplant complications including infections to be explored more readily.