Evidence for a sequential transfer of iron amongst ferritin, transferrin and transferrin receptor during duodenal absorption of iron in rat and human

Table 1 Ferritin and transferrin concentrations in rat duodenum under various iron status conditions

Parameter	Control	Iron deficient	Iron excess
Ferritin (ng/mg protein)
Lumen	126.0a± 61.42	105.8a± 35.81	228.8c± 73.54
Mucosa	308.3c± 123.36	256.0c± 1.19	731.5e± 191.96
Transferrin (μg/mg protein)
Lumen	10.9b± 7.6	11.1b± 10.3	6.8b± 4.7
Mucosa	0.87d± 0.79	0.80d± 1.20	0.61d± 0.63

Values with different superscript letters within each column and row are significantly different at ^a,c,eP < 0.005 for ferritin and ^b,dP < 0.001 for transferrin by one way ANOVA (n = 5).

Table 2 Summary of in situ grading of sequential autoradi-ographic and immunohistochemical staining signals

Radioactiveiron/protein	Iron status	Basal	5 min	15 min	30 min	2h
59Fe	ID	-	SUR+	IE+++	IE+++	-
	OL	-	SUR+++	IE±	IE±	-
Tf	ID	IV±	IV++	IE+++		IE+
				IV++		IV++
	OL	IV±	IE±	IE±
			IV±	IV±
TfR	ID	SUR±	SUR++	IE++	IE+	SUR±
	OL	SUR±	SUR++	SUR+	-	-
Fe	ID	IE±				IE±
		IV±	-	-
	OL	IE±	-		IE±	IE±
						IV+++

Tf: transfferin; TfR: Transferrin receptor; Fe: Ferritin; ID: Iron deficient; OL: Iron overload; IE: Intra epithelial; IV: Intra vascular; SUR: Surface; Grading +: minimal staining; ++: good; +++: intense; –: nil.

Table 3 Classification of human subjects according to iron status indicators

	Sex	No	Age (yr)	Hb (g/dL)	PCV	RBC M/cu mm	Serum ferritin (μg/L)
Normal	M	12	36.5 ± 10.6	14.8 ± 0.9	44.5 ± 3.3	5.8 ± 0.7	43 ± 22.1
	F	1	7.2	12.4	36	4.5	71.7
Iron deficient anemia	M	4	24.5 ± 20.9	7.4 ± 2.6	23.3 ± 9.0	4.1 ± 1.7	7.2 ± 4.0
	F	2	20.5	7.3	26.5	3.5	6.5
	M	10	44.3 ± 16.5	11.1 ± 1.64	33.6 ± 5.2	4.5 ± 1.4	75.3 ± 32.2
Anemia	F	4	21 ± 6.6	6.8 ± 3.0	20.8 ± 9.0	2.1 ± 1.2	57.4 ± 13.4
Iron supplements	F
Blood transfusion	M	1	32	9.5	29	4.7	28.6
Iron injection	F	1	32	8.4	27	4.3	101
Oral iron	F	1	20	9.7	30	3	38

Values are mean ± SD. Cut off values for defining deficiency, Hb: Male < 13 g/dL, Female < 12 g/dL, serum ferritin < 12 μg/L.