SERUM FERRITIN ACCURATELY PREDICTS NEED FOR COLONOSCOPY IN PATIENTS WITH ANEMIA

Abstract

Purpose: Evaluate the prevalence of colorectal cancer (CRC) in patients with anemia and ferritin of <50 ng/ml (low), 50 to 100 ng/ml (low normal), >100 ng/ml (normal) and compare that to a control group of non-anemic persons undergoing screening colonoscopy. Methods: The computerized endoscopy database at a VA medical center was searched from 1997 to 2003. All patients undergoing colonoscopy for evaluation of anemia were identified. Patients with overt or occult GI bleeding, h/o GI pathology (including polyps) or family h/o colon cancer were excluded. Medical charts were reviewed and data collected. A priori, subjects were stratified by serum ferritin: <50 ng/ml, 50–100 ng/ml and >100 ng/ml. Controls were defined as a-symptomatic, non-anemic patients undergoing screening colonoscopy. The prevalence of CRC was determined in each group. Results were compared using t tests and contingency table analysis with Fischer's exact test. Results: 414 case subjects and 323 controls met inclusion criteria. 97% of subjects were male, 96% were white with average age of 70 years. 94% of controls were male, 99% were while with average age of 66 years. The prevalence of CRC in patients with ferritin <50 ng/ml, 50–100 ng/ml, >100 ng/ml and controls was 5.9% (15/254), 2.2% (1/45), 0.86% (1/115) and 0.6% (2/323) respectively. The ODDS RATIO for CRC in the above groups was 9.8, 7.6, 1.4 and 1.0 respectively. There was a statistically significant difference between prevalence of CRC in patients with ferritin <50 ng/ml and ferritin >100 ng/ml (p = 0.02) or controls (p = 0.005). There was no significant difference between patients with ferritin <50 ng/ml and ferritin 50–100 ng/ml (p = 0.48) or between ferritin >100 ng/ml and controls (p = 0.55). Conclusions: Borderline IDA (ferritin 51–100 ng/ml) should be treated with the same degree of concern as IDA. Patients with anemia and serum ferritin >100 ng/ml do not have increased prevalence of CRC. Age appropriate CRC screening is adequate evaluation for this group.Figure 1