Anemia after traumatic spinal cord injury. The incidence and natural history of anemia in patients with spinal cord injuries (SCI) were investigated in a prospective study of 68 patients consecutively admitted to a regional acute SCI unit. Fifty had SCI and 18 had spine injuries (SI) without neurologic deficit. Thirty-six of 41 males (88%) and six of nine females (67%) with SCI were anemic on at least one occasion. In the first two weeks after injury, in females and in males, there was no significant difference in mean hemoglobin level between SI and SCI patients. At six weeks, no male with SI was anemic, and males with SCI had significantly lower mean hemoglobin levels than those with SI (121.6 g/L vs 145.4 g/L, p less than .001). Identified early causes of anemia were blood loss due to bony soft tissue or visceral injury, gastrointestinal bleeding, and surgery. In the postacute phase (more than six weeks after injury), anemia occurred in 25 of 41 male and three of nine female SCI patients, and its occurrence was associated with the presence of an identified chronic disease, especially urinary tract infection. 