Should patients with anemia and low normal or normal ferritin undergo colonoscopy?
Abstract & Commentary
By Malcolm Robinson, MD, FACP, FACG, Emeritus Clinical Professor of Medicine, University of Oklahoma College of Medicine, Oklahoma City. Dr. Robinson reports no financial relationship to this field of study.
Synopsis: In patients with anemia, serum ferritin levels below 100 ng/ml predict advanced neoplasia at colonoscopy.
Source: Mandeep S, et al. American Journal of Gastroenterology. 2007;102:82-88.
Colon cancer is the second most common cause of cancer-related mortality in the U.S. Since iron deficiency anemia is often associated with colon cancer, colonoscopy in patients with iron deficiency is recommended. In the past, studies have demonstrated that serum ferritin less than 50 ng/ml is associated with a high prevalence of colon neoplasia. However, the potential association of advanced colon neoplasia with ferritin levels above 50 ng/ml is unknown. In this VA study, carefully selected populations (from a total of 6,885 patients having colonoscopy) included 414 anemic (Hemoglobin less than 13 grams) patients who underwent colonoscopy and 323 normal risk nonanemic individuals having screening colonoscopy. The study was intended to compare advanced colon neoplasia prevalence in anemic patients with ferritin levels less than or equal to 50 ng/ml, 50-100 ng/ml, or greater than 100 ng/ml with findings in a nonanemic population seen for screening colonoscopy. In the <50 ng/ml group, advanced colon neoplasia (invasive colon cancer, malignant or dysplastic polyps) was found in 7.2% of exams vs 7.9% in patients who had >50 but <100 ng/ml ferritin. In the group with >100 ng/ml serum ferritin, 1.7% had advanced colonic neoplasia found as compared to 1.2% in the screening colonoscopy group. Of the patients in the <50 ng/ml group, 6.3% had invasive colon cancer. The authors point out that ferritin data were not available in the normal screening colonoscopy group. This study was summarized as indicating that there is a similarly high risk of colon neoplasia in patients with serum ferritin levels between 50-100 ng/ml as compared to ferritin levels below 50 ng/ml.
Commentary
Although this study is mostly limited to the older male patients found in the Veterans Administration setting of this study, it is likely that the results can be generalized to broader population groups. Thus, serum ferritin levels under 100 ng/ml should be a strong indication for colonoscopic evaluation of anemic patients. However, it should not be forgotten that a small but significant number of nonanemic individuals and anemic patients with higher ferritin levels may still have advanced colonic neoplasia. The cutoff point for anemia at 13 grams is appropriate in the overall VA population but may not be as appropriate in the different gender mix of the general population. In any case, screening colonoscopy remains appropriate in the general population over age 50. The importance of these new VA data may be to help persuade otherwise reluctant patients to undergo procedures that may be lifesaving in a much higher than average risk setting.
In patients with anemia, serum ferritin levels below 100 ng/ml predict advanced neoplasia at colonoscopy.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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