Cutoff Value of Serum Ferritin Requiring Gastrointestinal Endoscopic Evaluation for Anemia

The laboratory test with the highest sensitivity and specificity for the diagnosis of iron deficiency anemia (IDA) is serum ferritin. Chronic blood loss, one of the common causes of IDA in adults, is often associated with an occult gastrointestinal (GI) malignancy, especially in adult males and postmenopausal females. It is difficult to set the cutoff ferritin level for GI endoscopic evaluation in adult patients with anemia which is presupposed to result from GI malignancies. To answer this question, we conducted a retrospective study to find out the optimum values of serum ferritin and other hematologic indices in adult anemic patients to be referred for thorough GI endoscopic evaluation.

We reviewed retrospectively patients' medical records. The subject of study was adult anemic patients (n=544) at Konkuk University Medical Center who underwent upper and lower GI endoscopy to search for possible GI blood loss from August 2005 to August 2009. Patients were stratified into three groups according to the results of GI endoscopy: benign group vs. premalignant group vs. malignant group.

Among a total of 544, benign, premalignant and malignant diseases were detected in 265, 220 and 59 patients, respectively. The prevalence of GI malignant diseases was 10.8% (59/544) for all patients, 13.9% (34/244) for male patients and 8.3% (25/300) for female patients. As compared to non-malignant groups (benign and premalignant), malignant group demonstrated statistically significant differences in terms of median values of age (56 vs. 66 vs. 70 years, P < 0.001), male gender (41.89 vs. 45 vs. 57.63%, P = 0.0367), MCV (86.7 vs. 88.2 vs. 78.6 fL, P = 0.0005), ferritin (69.39 vs. 108.5 vs. 21.7 ng/mL, P = 0.0002), Fe (35 vs. 38 vs. 13.5 μg/dL, P < 0.001), TIBC (279 vs. 259 vs. 320 μg/dL, P = 0.0024), and TIBC saturation (13.07 vs. 14.78 vs. 4.64%, P < 0.001). However, Hb, Hct and RDW did not show significant differences. By ROC curve analyses to find out optimum cut-off points of the serum ferritin and TIBC saturation which distinguish between non-malignant diseases and malignant diseases, the cut-off ferritin value of 44.33 ng/mL in male had a sensitivity of 72.73% and a specificity of 70.95% (AUC 0.705 and P = 0.0001). In contrast, ROC curve analyses were not useful for ferritin in female (AUC 0.609 and P =0.0787). The cut-off TIBC saturation value of 9.13% in male had a sensitivity of 73.33% and a specificity of 70.92% (AUC 0.750 and P = 0.0001). And the cut-off TIBC saturation value of 6.16% in female had a sensitivity of 69.57% and a specificity of 65.13% (AUC 0.643 and P = 0.0262).

Our study proposes that adult male patients with anemia require thorough endoscopic evaluation to detect GI malignancy when their serum ferritin levels are ≤ 44 ng/mL or TIBC saturation values are ≤ 9%. For adult female anemic patients, only TIBC saturation values less than 6% may contribute to determining whether they require GI endoscopic evaluation.

No relevant conflicts of interest to declare.