Recent Versus Conventional Iron Status Parameters for Diagnosis of Anemia in Juvenile Idiopathic Arthritis Patients

Objective: Juvenile Idiopathic Arthritis (JIA) is commonly associated with different types of anemia. The diagnosis and treatment of IDA is a medical necessity; being a well-recognized cause of both short and long term morbidity plus being strongly related to poor disease outcome. In the presence of concomitant chronic illness or inflammation, the diagnosis of iron deficiency using the conventional laboratory parameters is a major medical challenge. Therefore, the utility of two recent iron status parameters; hepcidin-25 "active form of iron metabolism negative regulator” and reticulocyte hemoglobin content (CHr) “functional anemia indicator” was compared to that of two conventional ones; transferrin saturation (TSAT) and red cell distribution width percentages (RDW%) in diagnosing iron deficiency anemia in patients with JIA.

Methods: Blood samples were obtained from 43 JIA patients whose ages ranged from 3 to 16 years and 20 age and sex matched healthy children as control group. Three different types of anemia; iron deficiency anemia (IDA), anemia of chronic disease (ACD) and combined anemia (IDA/ACD) were identified within the studied patients using iron profile, ESR and C-reactive protein. Serum hepcidin-25 was assessed by ELISA technique; CHr, TSAT% and RDW% were all estimated using Siemens ADVIA 2120 analyzer in patients and the control group.

Results: Anemia was identified in 22 (51.2%) patients. Serum hepcidin-25 and TSAT% were significantly lower in IDA than ACD & IDA/ACD patients (p= 0.032 and p=0.034 for hepcidin and p= 0.004 and p=0.012 for TSAT%). Significantly lower CHr and higher RDW% were found in IDA/ACD compared to ACD patients (p= 0.032 and p< 0.001, respectively). Serum hepcidin ≤ 3.8ng/mL and TSAT% ≤ 5.8% differentiated IDA from both ACD and IDA/ACD with 80 and 100% sensitivity and 88.24% specificity. CHr ≤24.4pg and RDW % > 16.4% showed 80 and 90% sensitivity and 100% specificity; distinguishing IDA/ACD from ACD.

Conclusion:Serum hepcidin and CHr were not superior to TSAT% and RDW%; discriminating among different types of anemia in JIA patients.

Table 1: Comparison between anemia subgroups according to CHr and serum hepcidin

	IDA (n=5)	ACD (n=6)	Combined anemia (n=7)	Control (n=20)	p
CHr (pg)	23.61 ± 3.80a	27.36 ± 2.30b	23.37 ± 3.18a	30.54 ± 1.99	<0.001*
Serum hepcidin (ng/ml)	3.60 (3.0–4.9)bc	5.10 (3.10 – 90.0)	7.15 (3.1–60.0)	5.0 (0.10–10.8)	0.121

Data was expressed as Mean ± SD. for normally distributed data and Median (Min. – Max.) for abnormaly distrbutied data

a: Significant with control gorup

b: Significant with combined anemia group

c: Significant with ACD group

Table 2: Comparison among anemia subgroups and control group according to RDW & TSAT% 

	IDA (n=5)	ACD (n=7)	Combined anemia (n=10)	Control (n=20)	Test of sig.	p
RDW%
Min. – Max.	17.30 – 19.90	13.10 – 16.40	15.60 – 22.0	12.40 – 15.80	F= 45.032*	<0.001*
Mean ± SD.	18.42 ± 1.04	14.49 ± 1.30	18.46 ± 1.92	13.47 ± 0.86
Median	2.62	13.90	18.20	13.10
Schp*	p1<0.001*,p2=0.362,p3<0.001*,p4=1.000,p5<0.001*,p6<0.001*

TSAT %
Min. – Max.	4.20 – 5.80	6.0 – 20.50	4.40 – 26.0	11.0 – 40.0	KWχ2=*	<0.001*
Mean ± SD.	4.78 ± 0.64	10.73 ±4.82	13.82 ± 8.63	22.71 ± 8.32
Median	4.50	10.0	12.80	20.70
MWp1	0.001*	0.001*	0.016*
MWp2	0.012*	0.660
MWp3	0.004*

 ^KWc²: Chi square for Kruskal Wallis test F: F test (ANOVA)

p₁: p value for comparing between control and IDA

p₂: p value for comparing between control and ACD

p₃: p value for comparing between control and combined anemia

p₄: p value for comparing between combined anemia and IDA

p₅: p value for comparing between combined anemia and ACD

p₆: p value for comparing between ACD group and IDA group

MW: Mann Whitney test Sch: Post Hoc Test (Scheffe)

*: Statistically significant at p ≤ 0.05

Table 3: Agreement (sensitivity, specificity and accuracy) for serum hepcidin and TSAT% with IDA vs. ACD and combined anemia in JIA patients

			ACD and combined anemia		IDA		Sensitivity		Specificity		PPV		NPV		Accuracy
Serum hepcidin (ng/ml)	>3.8		15		1		80.0		88.24		66.67		93.75		86.36
	≤3.8		2		4
TSAT%		>5.8		15		0		100.0		88.24		71.43		100.0		90.91
		≤5.8		2		5

Table 4: Agreement (sensitivity, specificity and accuracy) for CHr and RDW% with ACD vs. combined anemia in JIA patients

			ACD		Combined anemia		Sensitivity		Specificity		PPV		NPV		Accuracy
CHr	>24.4		7		2		80		100.0		100.0		77.78		88.24
	≤24.4		0		8
RDW %		≤16.4		7		1		90.0		100.0		100.0		87.50		94.12
		>16.4		0		9