Paying attention to the ferritin level of an anemic person’s blood may help healthcare providers decide whether to order a colonoscopy to see if colon cancer is the problem. A study by researchers at the Minneapolis VA Hospital, reported in the January 2007 issue of the American Journal of Gastroenterology, found that looking at the ferritin level in persons with anemia may provide additional information on risk of colon cancer. One of the leading reasons to look for colon cancer is the presence of iron deficiency anemia, since bleeding from such a cancer may cause loss of iron from the body. Ferritin is a measure of how much iron your body has stored for future use; low levels are considered diagnostic of iron deficiency. However, other conditions (such as inflammation) may increase ferritin and hamper recognition of iron deficiency.

For this retrospective study, the researchers examined the data on 414 people (almost all older men) who had a colonoscopy because they had anemia and 323 people who had no symptoms or anemia but had a colonoscopy as a routine screening for colon cancer. All subjects in the study had no abdominal symptoms and no documented intestinal bleeding. The mean age of those studied was 69 years old. All those with anemia also had measurement of ferritin shortly before the colonoscopy was performed. The authors studied four groups: those with no anemia, and those with anemia who had ferritin levels that were low (50 ng/mL or less), low normal (51-100 ng/mL), or not low (above 100 ng/mL).

As expected, those with iron deficiency (low ferritin) were significantly more likely to have a cancerous or pre-cancerous condition in the colon (called advanced colonic neoplasia). However, those with anemia and low normal ferritin were just as likely to have advanced colonic neoplasia. In contrast, those with anemia but without low or low normal ferritin were no more likely to have advanced colonic neoplasia than those who did not have anemia.

Ferritin Below 100 ng/mL: An Indicator

When age was factored in, the people with serum ferritin levels below 100 ng/mL were almost 5 times more likely to have colon cancer or high-risk types of polyps, observed the researchers. For men with unexplained anemia, the researchers concluded that a ferritin level below 100 ng/mL is a reason to promptly refer these patients for colonoscopy. The test helps determine if the anemia is related to colon cancer.

Source
Sawhney MK, Lipato T, Nelson DB et al. Should patients with anemia and low normal or normal serum ferritin undergo colonoscopy? Amer J Gastroenterol. 2007:102;82-88.