Variable	Iron Deficiency Anemia	Anemia of Chronic Disease
Epidemiology	Most common overall	Most common in hospitalized patients
Type of anemia	Normocytic-normochromic (early stage); microcytic-hypochromic (later stage)	Normocytic-normochromic (60%-70% of cases); microcytic-hypochromic (30%-40% of cases)
Principal lesion	Anemia secondary to a lack of adequate iron	Suppression of erythropoiesis by mediators of an inflammatory response
Erythrocyte sedimentation rate	<-->
Hematocrit, %	<31-32 (<0.31-0.32)	28-32 (0.28-0.32)
Mean corpuscular volume		<-->
Mean corpuscular hemoglobin		<-->
Mean corpuscular hemoglobin concentration		<-->
RBC distribution width†	(>14%)	<--> to
Serum iron concentration
Total iron binding capacity
Transferrin saturation (%)†	(<10-15)	to <-->
Ferritin concentration, ng/mL (µg/L)†	(<10 [<10])
Free erythrocyte protoporphyrin concentration		<--> to
Stainable marrow iron	Absent	Plentiful

, decreased; , increased; <-->, within normal limits.

* Adapted from Cook and Skikne,[23] Worwood,[24] Duffy,[28] and Allen et al.[29]

† Value(s) in parentheses are typical for this variable.

	Group
Variable	IDA	ACD	Reference Interval	P†
Serum iron concentration, µg/L	153 ± 79	167 ± 93	F, 260-1,700; M, 760-1,980	.4885
TIBC, mg/L	4.32 ± 0.84	1.98 ± 0.55	2.62-4.74	<.0001
Transferrin saturation, %	3.7 ± 2.2	9.0 ± 4.5	20-50	<.0001
Ferritin concentration, ng/mL (µg/L)	6.7 ± 4.4 (6.7 ± 4.4)	1,052.0 ± 970.6 (1,052.0 ± 970.6)	F, 12-160 (12-160); M, 18-250 (18-250)	<.0001
RBC count, ´ 10[6] /µL (´ 10[12] /L)	3.8 ± 0.7 (3.8 ± 0.7)	3.2 ± 0.6 (3.2 ± 0.6)	F, 3.8-5.5 (3.8-5.5); M, 4.3-6.2 (4.3-6.2)	.0011
Hemoglobin concentration, g/dL (g/L)	8.8 ± 2.0 (88 ± 20)	9.5 ± 1.7 (95 ± 17)	F, 12.0-15.2 (120-152); M, 13.2-15.2 (132-152)	.0936
Hematocrit, %	27.4 ± 5.8 (0.27 + 0.6)	28.3 ± 5.0 (0.28 ± 0.05)	F, 37-46 (0.37-0.46); M, 40-52 (0.40-0.52)	.4761
Mean corpuscular volume, µm[3] (fL)	72.6 ± 9.8 (72.6 ± 9.8)	87.5 ± 7.8 (87.5 ± 7.8)	F, 79-101 (79-101); M, 82-105 (82-105)	<.0001
Mean corpuscular hemoglobin, pg	23.3 ± 3.9	29.5 ± 2.9	F, 27-33; M, 28-34	<.0001
Mean corpuscular hemoglobin concentration, g/dL (g/L)	32.0 ± 1.3 (320 ± 13)	33.7 ± 0.7 (337 ± 7)	31-35 (310-350)	<.0001
RBC distribution width, %	18.4 ± 5.1	14.0 ± 1.8	11.5-13.5	<.0001

ACD, anemia of chronic disease; IDA, iron deficiency anemia.

* Data are given as mean ± SD unless otherwise indicated.

† IDA vs ACD group by unpaired Student t-test analysis.

Variable	AUC	P	Cutoff	Sensitivity (%)	Specificity (%)	PPV (%)	NPV (%)
TIBC	0.993	.164*	3.15 mg/L	92.7	100.0	100.0	91.2
TfR	0.958	.045†	29.5 nmol/L	92.7	83.9	88.4	89.7
MCV	0.873	.501‡	79.8 µm[3] (79.8 fL)	80.5	83.9	86.8	76.5
%TS	0.834	.996§	6%	92.7	61.3	76.0	86.4
RDW	0.834	<.001||	14.8%	75.6	77.4	81.6	70.6
SIC	0.535	--	140 µg/L	51.2	64.5	65.6	50.0

ACD, anemia of chronic disease; AUC, area under the curve; IDA, iron deficiency anemia; MCV, mean corpuscular volume; NPV, negative predictive value; PPV, positive predictive value; RDW, RBC distribution width; SIC, serum iron concentration; TfR, transferrin receptor; TIBC, total iron binding capacity; %TS, percent transferrin saturation.

* AUC for TIBC vs TfR.

† AUC for TfR vs MCV.

‡ AUC for MCV vs %TS.

§ AUC for %TS vs RDW.

|| AUC for RDW vs SIC.