Should Patients With Anemia Without Iron Deficiency Undergo Colonoscopy?
Should Patients With Anemia Without Iron Deficiency Undergo Colonoscopy?
Background: Patients with unexplained iron deficiency anemia have a greater prevalence of colonic neoplasia, and should be evaluated for a colonoscopy. The approach to patients with anemia without iron deficiency remains unclear.
Objective: To compare the prevalence of colonic neoplasia in anemic patients with normal ferritin (>50 ng/mL), to those with ferritin ≤50 ng/mL, and nonanemic individuals.
Methods: Patients referred for colonoscopy for anemia evaluation were stratified into 3 groups: ferritin ≤50 ng/mL, 51-100 ng/mL, and >100 ng/mL. We compared these groups to each other, and to asymptomatic nonanemic individuals undergoing screening colonoscopy. The prevalence of advanced colonic neoplasia was determined for each group using existing records.
Results: During the study period, 414 patients who underwent colonoscopy for anemia evaluation and 323 nonanemic individuals who underwent colonoscopy for cancer screening met inclusion criteria. Study subjects were mostly men. The prevalence of advanced colonic neoplasia in subjects with ferritin 51-100 ng/mL was 7.2% (95% CI 2.4-17.9%), similar to 7.9% (95% CI 5.1-11.9%) in those with ferritin ≤50 ng/mL. The incidence of advanced colonic neoplasia in subjects with ferritin >100 ng/mL was 1.7% (95% CI 0.1-6.6%), similar to 1.2% (95% CI 0.4-3.3%) in the asymptomatic nonanemic group. After adjusting for age, patients with ferritin ≤50 ng/mL and 51-100 ng/mL were almost 5 times more likely to harbor advanced colonic neoplasia than the other groups. The addition of other laboratory parameters did not improve the predictive value of ferritin.
Conclusion: A ferritin cutoff of 100 ng/mL can be used to determine the need for colonoscopy in men with anemia.
Colon cancer is the second most common cause of cancer-related mortality in the United States. Iron deficiency anemia is a well-recognized sign of colon cancer. There is broad consensus among physicians that persons with unexplained iron deficiency anemia be considered for a colonoscopy to exclude colonic neoplasm. The diagnosis of iron deficiency anemia should be firmly established before patients are subjected to costly and invasive procedures. Serum ferritin has been proven to be the most accurate noninvasive test for the diagnosis of iron deficiency anemia, and is often used to select patients for colonoscopy. While prospective studies have shown that patients with serum ferritin <50 ng/mL have a high prevalence of colonic neoplasia and should undergo prompt colonoscopy, the prevalence of colonic neoplasia in anemic patients with ferritin level >50 ng/mL is not known. There are no established guidelines regarding the need for diagnostic colonoscopy in patients with anemia and serum ferritin >50 ng/mL. Ferritin is an acute phase reactant, and iron deficiency can be present in patients with ferritin levels of 51-100 ng/mL. Iron deficiency is however unlikely, even in the presence of concomitant medical illnesses, if ferritin levels are above 100 ng/mL.
Several studies have reported on the yield of colonoscopy in patients with iron-deficiency anemia. Most are limited to patients with ferritin <50 ng/mL. The determination of whether patients with anemia and ferritin levels of >50 ng/mL are at greater risk for colonic neoplasm is difficult due to the absence of comparison to a nonanemic control group. Prior to the use of screening colonoscopy, it was difficult to accurately ascertain the prevalence of colonic neoplasia in the normal population.
Should patients with anemia and serum ferritin >50 ng/mL undergo colonoscopy? Should patients with ferritin 50-100 ng/mL be evaluated differently from those with ferritin >100 ng/mL? To answer these questions, we conducted a study to determine the prevalence of colonic neoplasia in patients with anemia and serum ferritin 51-100 ng/mL, and >100 ng/mL. We also sought to compare the prevalence of colonic neoplasia in these patients to those with ferritin ≤50 ng/mL (high likelihood of iron deficiency anemia), and to asymptomatic, nonanemic persons undergoing screening colonoscopy.
Abstract and Introduction
Background: Patients with unexplained iron deficiency anemia have a greater prevalence of colonic neoplasia, and should be evaluated for a colonoscopy. The approach to patients with anemia without iron deficiency remains unclear.
Objective: To compare the prevalence of colonic neoplasia in anemic patients with normal ferritin (>50 ng/mL), to those with ferritin ≤50 ng/mL, and nonanemic individuals.
Methods: Patients referred for colonoscopy for anemia evaluation were stratified into 3 groups: ferritin ≤50 ng/mL, 51-100 ng/mL, and >100 ng/mL. We compared these groups to each other, and to asymptomatic nonanemic individuals undergoing screening colonoscopy. The prevalence of advanced colonic neoplasia was determined for each group using existing records.
Results: During the study period, 414 patients who underwent colonoscopy for anemia evaluation and 323 nonanemic individuals who underwent colonoscopy for cancer screening met inclusion criteria. Study subjects were mostly men. The prevalence of advanced colonic neoplasia in subjects with ferritin 51-100 ng/mL was 7.2% (95% CI 2.4-17.9%), similar to 7.9% (95% CI 5.1-11.9%) in those with ferritin ≤50 ng/mL. The incidence of advanced colonic neoplasia in subjects with ferritin >100 ng/mL was 1.7% (95% CI 0.1-6.6%), similar to 1.2% (95% CI 0.4-3.3%) in the asymptomatic nonanemic group. After adjusting for age, patients with ferritin ≤50 ng/mL and 51-100 ng/mL were almost 5 times more likely to harbor advanced colonic neoplasia than the other groups. The addition of other laboratory parameters did not improve the predictive value of ferritin.
Conclusion: A ferritin cutoff of 100 ng/mL can be used to determine the need for colonoscopy in men with anemia.
Introduction
Colon cancer is the second most common cause of cancer-related mortality in the United States. Iron deficiency anemia is a well-recognized sign of colon cancer. There is broad consensus among physicians that persons with unexplained iron deficiency anemia be considered for a colonoscopy to exclude colonic neoplasm. The diagnosis of iron deficiency anemia should be firmly established before patients are subjected to costly and invasive procedures. Serum ferritin has been proven to be the most accurate noninvasive test for the diagnosis of iron deficiency anemia, and is often used to select patients for colonoscopy. While prospective studies have shown that patients with serum ferritin <50 ng/mL have a high prevalence of colonic neoplasia and should undergo prompt colonoscopy, the prevalence of colonic neoplasia in anemic patients with ferritin level >50 ng/mL is not known. There are no established guidelines regarding the need for diagnostic colonoscopy in patients with anemia and serum ferritin >50 ng/mL. Ferritin is an acute phase reactant, and iron deficiency can be present in patients with ferritin levels of 51-100 ng/mL. Iron deficiency is however unlikely, even in the presence of concomitant medical illnesses, if ferritin levels are above 100 ng/mL.
Several studies have reported on the yield of colonoscopy in patients with iron-deficiency anemia. Most are limited to patients with ferritin <50 ng/mL. The determination of whether patients with anemia and ferritin levels of >50 ng/mL are at greater risk for colonic neoplasm is difficult due to the absence of comparison to a nonanemic control group. Prior to the use of screening colonoscopy, it was difficult to accurately ascertain the prevalence of colonic neoplasia in the normal population.
Should patients with anemia and serum ferritin >50 ng/mL undergo colonoscopy? Should patients with ferritin 50-100 ng/mL be evaluated differently from those with ferritin >100 ng/mL? To answer these questions, we conducted a study to determine the prevalence of colonic neoplasia in patients with anemia and serum ferritin 51-100 ng/mL, and >100 ng/mL. We also sought to compare the prevalence of colonic neoplasia in these patients to those with ferritin ≤50 ng/mL (high likelihood of iron deficiency anemia), and to asymptomatic, nonanemic persons undergoing screening colonoscopy.
