Significance of serum iron and ferritin in patients with colorectal adenomas

Colorectal adenomas are often detected on mass screening, although detection rates with fecal occult blood tests are low. The relationship between colorectal adenomas and the resulting blood loss was examined indirectly, using serum iron and ferritin levels.

Serum iron and ferritin concentrations were measured in 184 men with colorectal adenomas (> or = 1 cm in 92; < 1 cm in 92) and in 92 healthy male controls. Values in the three groups were compared. In the patients with adenomas > or = 1 cm, serum iron and ferritin levels were compared on the basis of the site, number, histology, and degree of dysplasia of the adenoma.

The mean serum iron level was significantly lower in patients with adenomas > or = 1 cm than in controls (P < 0.05), although this level did not differ significantly between those with adenomas < 1 cm and controls. The mean serum ferritin level also was significantly lower in patients with adenomas > or = 1 cm than in those with adenomas < 1 cm and controls (P < 0.05, P < 0.01, respectively), although this level did not differ between those with adenomas < 1 cm and controls. There was no difference in mean serum iron or ferritin levels on the basis of the site, number, histology, or degree of dysplasia of the adenoma.

We conclude that decreased serum iron and ferritin levels are related only to adenoma size and that adenomas > or = 1 cm may bleed steadily, resulting in iron deficiency. However, low dietary intake of iron and fiber may be one of the causes of low serum iron and ferritin.