1. Introduction
Iron deficiency anemia (IDA) has been recognized as a common nutritional problem in infants and young children in developing countries [1] . It has been reported that more than half of children in developing countries suffer from IDA mainly due to poor nutrition in the majority of cases [2] . Many studies have demonstrated that IDA is associated with poor learning ability, poor memory, lack of concentration, educational failure and affects child cognitive and motor development [3] [4] .
Knowledge about the causes of IDA in order to develop treatment and prevention strategies should be in the top of health research agenda, especially in the developing countries. Numerous risk factors for IDA have been recognized such as inadequate iron intake and absorption, increased requirements of iron during growth, and excessive losses of iron. Recently, Helicobacter pylori (H. pylori) infection has been suggested as a possible etiology for IDA [5] .
H. pylori infection is a highly prevalent microbial chronic infection across the world affecting nearly half of the global population with a high variation in prevalence in different countries, age groups, and socioeconomic standards. The prevalence of infection ranges from over 80% in developing low socioeconomic countries to less than 40% among developed countries [6] . It has been reported that 65% of children in developing countries are infected with H. pylori [7] . In children, it was proposed that H. pylori infection is associated with gastrointestinal disorders as recurrent abdominal pain, dyspepsia, chronic gastritis and peptic ulcers [8] . Moreover, it was reported that H. pylori may be also associated with several extra-gastrointestinal diseases such as idiopathic thrombocytopenic purpura, anemia and some allergic diseases [9] .
In 1991, Blecker et al. [10] suggested the association between H. pylori infection and IDA and after that several studies had been conducted to assess the role of infection in IDA [11] [12] . In 2008, a systematic review demonstrated a positive relation between H. pylori infection and depletion of iron stores both in adults and children [13] . However, the controversy still exists about association between H. pylori infection and IDA [9] .
The aim of this study was to evaluate the association between H. pylori infection and IDA among school age children in Sohag University Hospital.
2. Subjects and Methods
2.1. Study Design and Place
This was a prospective case-control study conducted in Pediatric Department, Sohag University Hospital, Sohag, Upper Egypt in the period from March 2015 to February 2016.
2.2. Patients
The present study included 200 school-age children (127 males and 73 females) with established diagnosis of IDA and mean age of 7.7 ± 1.35 year (range 5 - 10 years, median = 8 years). All patients were recruited from children attending Pediatric outpatient clinic in Sohag University Hospital, Sohag, Upper Egypt. Also the study included 50 apparently healthy age and sex matched children who attend pediatric outpatient clinic for different complaints (cough, diarrhea, etc.), as a control group.
2.3. Inclusion Criteria
School age children (6 - 12 years) diagnosed with iron deficiency anemia.
2.4. Exclusion Criteria
Children with BMI for age less than 5th percentile.
Children with positive stool analysis for parasitic infestation.
Anemic children due to causes other than IDA.
2.5. Ethical Consideration
The protocol of the study was approved by Sohag University Hospital Ethical Committee and written informed consent was obtained from parents of all participants in accordance to Sohag University Hospital Ethical Committee guidelines.
2.6. Methods
Blood was withdrawn into standard EDTA vacutainers for the assay of CBC, plain tubes for the assay of ferritin, iron, TIBC, and H. pylori IgG antibodies. Separated serum was divided in aliquots. One aliquot was used for estimation of ferritin, iron and TIBC and the rest of aliquots were stored at −70˚C to be used for estimation of H. pylori IgG antibodies.
Laboratory Investigations
Complete blood count (CBC) was done by the use of cell dyne-3700 (Abbott Diagnostics, Dallas, USA). Serum ferritin was done by the use of Architect 2000 system (Abbott Diagnostics, Dallas, USA). H. pylori IgG was measured using ELIZA kit (R-Biopharm AG, Anderneuren Bergstrabe 17, 64,297 Darmstadt, Germany). Serum iron and total iron binding capacity (TIBC) were done by the use of Cobas-C311 (Roch Diagnostics, Mannheim, Germany). All of the included individuals underwent a quantitative detection of H. pylori IgG antibodies
2.7. Statistical Analysis
Statistical analysis was performed using Statistical Package for Social Sciences (SPSS version 22). All data was expressed as mean ± SD. Student t test was used to compare means between different groups. Correlation Coefficient (r) was used for showing positive and negative correlation between variables. P value is considered significant if less than 0.05.
3. Results
The study was carried out on 200 children with IDA (127 males and 73 females) and 50 apparently healthy age and sex matched controls. Age, hematological data and H. pylori specific IgG titer of patients are represented in Table 1.
The serological investigations for H. pylori infection revealed that 72 cases (36%) of IDA patients and 6 cases (12%) of non-anemic controls had positive antibody level for H. pylori specific IgG and the difference between the two groups was statistically significant (P = 0.036) Table 2.
H. pylori specific IgG antibody titer showed significant positive correlation with age and significant negative correlation with each of Hb level, MCV, HCT and serum ferritin, Table 3 and Figure 1.
Comparison between H. pylori positive and H. pylori negative IDA patients revealed that the mean age of H. pylori positive IDA cases is significantly higher than that of H. pylori negative IDA cases, with male predominance in H. pylori positive patients. Also it showed that hematological parameters (Hb, MCV & HCT) and serum ferritin were significantly lower in H. pylori positive IDA patients than H. pylori negative IDA cases, Table 4.
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Table 1. Hematological data of the study group.
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Table 3. Pearson correlation statistics between H. pylori antibody titer and both of age and laboratory investigations.
4. Discussion
H. pylori infection has a higher prevalence rate in developing than developed countries and has been reported in 50% of 10 year old children [14] . In Egypt, the prevalence of H. pylori infection among school age was 72.38% as reported by Mohamed et al., in 2008 [15] . H. pylori was discovered in 1983 by Marshall and Warren [16] in the stomach of peptic ulcer patients. However, it is now agreed that H. pylori is not only associated with peptic ulcer, but also with wide spectrum of gastrointestinal disorders varying from asymptomatic gastritis to gastric carcinoma [17] . Moreover, it was reported that H. pylori may be also associated with several extra-gastrointestinal diseases such as IDA, idiopathic thrombocytopenic purpura, and some allergic diseases [9] . On the other hand, H. pylori infection is mostly asymptomatic and nearly 20% of infected people develop a clinical disease, usually in adulthood [18] .
The mechanism of association between H. pylori infection and IDA was proposed by several pathways which may include consumption of iron by the organism itself, gastrointestinal blood loss and decrease in iron absorption due to low levels of gastric acid [12] [13] .
In this study we aimed to evaluate the association between H. pylori infection and IDA among school-age children. The results of this study revealed that there was a significantly higher rate of H. pylori infection among studied group than healthy controls, demonstrating significant association between H. pylori infection and IDA among school age children. This came in agreement with Darvishi et al., [19] who reported an association between H. pylori infection and IDA among pediatric patients where they found that 80.3% of IDA cases and 14% of non-anemic controls had a positive antibody titer for H. pylori infection and the difference between two group was statistically significant (P < 0.0001). In addition several other studies have shown this association [20] [21] [22] [23] [24] . Moreover, four meta-analyses including both pediatric and adult patients have shown an association between H. pylori infection and IDA [5] [13] [25] [26] . Based on the results of these studies, the new guidelines of the last Maastricht Florence Consensus Report recommended to search and eradicate H. pylori
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Table 4. Comparison between H. pylori positive and H. pylori negative IDA patients.
infection in IDA after exclusion of bleeding from gastrointestinal tract [27] [28] . On the other hand some studies did not support the association between H. pylori infection and IDA [14] [29] [30] [31] . Discrepancies of results among different studies may be attributed to differences in study design, number of patients, inclusion criteria, ethnicity and H. pylori species [19] [28] [32] .
Results of the current study revealed that H. pylori IgG specific antibody titer had a significant negative correlation with each of Hb level, MCV, HCT and serum ferritin. This agree with an analytical Iranian study on school-age children, where it showed a significant negative correlation between H. pylori antibody level with serum iron and ferritin (P < 0.001) [33] . Also in another study, H. pylori seropositivity was associated with a tendency to a lower ferritin levels in Arab children in Palestine [34] .
In the present study, there was a significant positive correlation between H. pylori IgG titer and age and the mean age of H. pylori positive IDA cases was significantly higher than that of H. pylori negative IDA cases. This was in agreement with Baggett et al., [22] who reported that H. pylori infection was associated with older age and the association between iron deficiency and H. pylori infection was modified by age, with the strongest association in children who were aged ≥9 years. The increased risk in older children seems biologically reasonable as older children are likely to have been infected for longer than younger children, allowing more time for iron deficiency to develop. Similarly, an age-dependent association between H. pylori and IDA was reported among South Korean children [35] .
The present work showed significant male predominance in H. pylori positive IDA patients. This came in agreement with the study done by Zamani et al., who reported that H. pylori infection was significantly more common in boys than girls (p = 0.029) [2] .
The current study showed that parameters of iron deficiency anemia (Hb, MCV, HCT and serum ferritin) were significantly lower in H. pylori positive IDA patients than those of H. pylori negative IDA cases. This finding showed the negative effect of H. pylori infection on iron stores and indicated that H. pylori infection may increase the severity of anemia and support the findings of other studies which suggested that eradication of H. pylori infection improve IDA treatment and help improvements in iron status [10] [19] [36] . In 2010, Zhang et al., in a meta-analysis [37] , found that H. pylori infection may impair the absorption of oral ferrous and elimination of the infection may improve the treatment of iron-deficiency. Also, in another meta-analysis, Yuan et al., [26] had reported similar results.
5. Conclusion
In conclusion, the results of this study demonstrate significant association between positive serology for H. pylori infection and IDA in school-age children. Moreover, infection may increase the severity of anemia.
6. Limitations of the Study
In this study, due to limited resources, the existence of H. pylori infection was assessed using only one test (H pylori specific IgG antibody titer). High prevalence of H. pylori infection in Egypt, and local prevalence could affect positive predictive value of the used test.
Acknowledgements
The authors are grateful to all who participated in the study.
Conflict of Interest
The authors declare that they have no competing interests.