A guide to diagnosis of iron deficiency and iron deficiency anemia in digestive diseases

Table 1 Causes of iron deficiency anemia

Digestive disorders

Increased losses of iron

Cancer/polyp: colon, stomach, esophagus, small bowel

Peptic ulcer, esophagitis

NSAID use

Inflammatory bowel disease: ulcerative colitis, Crohn's disease

Intestinal parasites

Vascular lesions: angiodysplasia, watermelon stomach

Meckel’s diverticulum

Reduced iron absorption

Celiac disease

Bacterial overgrowth

Whipple’s disease

Lymphangiectasia

Gastrectomy (partial and total) and gastric atrophy

Gut resection or bypass

Urological and gynecological disorders

Intravascular hemolysis

Prosthetic valves and cardiac myxomas, paroxysmal nocturnal hemoglobinuria, marathon runners, multiple blood donations

Deficient iron intake

Table 2 Differences between the serum values of iron-deficiency anemia, anemia of chronic diseases, and anemia of mixed origin

	Iron-deficiency anemia	Anemia of chronic diseases	Anemia of mixed origin
Serum iron	Decreased	Decreased	Decreased
Transferrin	Increased	Decreased or normal	Decreased
Transferrin saturation	Decreased	Decreased	Decreased
Ferritin1	Decreased (< 30 ng/mL)	Increased (> 100 ng/mL)	Normal
Soluble transferrin receptor	Increased	Normal	Increased or normal
C-reactive protein	Normal	Increased	Increased
Erythropoietin	Increased	Normal or slightly increased for the degree of anemia	Increased or normal

¹Ferritin values between 30 and 100 ng/mL: Make other determinations to differentiate the two entities.