Factors that decrease collagen synthesis include all of the following except:

C. Anemia.

DISCUSSION: Collagen synthesis, an integral part of wound healing, is affected by many local and systemic factors. Protein depletion impairs fibroplasia. Hypoproteinemia leads to diminution of fibroblast proliferation, proteoglycan and collagen synthesis, angiogenesis, and wound remodeling. Although anemia was once believed to be a significant cause of wound disruption, studies have shown that, in the absence of malnutrition or hypovolemia, anemia with a hematocrit greater than 15% does not interfere with wound healing. In contrast, molecular oxygen is critical for collagen synthesis because it is one of the factors required for the hydroxylation of lysine and proline. Also, hypoxia favors wound infection. The role of age in collagen synthesis is not clear, but the incidence of wound failure and incisional hernias is greater in patients older than 60. Fibroplasia occurs at a slower rate in older animals. Perhaps more than any other factor, wound infection is associated with the risk of wound failure.