[Effect of Helicobacter pylori infection on iron status among preschool children]

To explore the relationship between Helicobacter pylori (Hp) infection and iron status using serum ferritin (SF) as a marker for total iron and to identify the related factors of iron nutritional status among preschool children.

By cluster sampling, we recruited 475 preschool children aged 2 to 7 years. A structured questionnaire and diet form were sent to the parents of these children to obtain related information about the socioeconomic level and dietary intakes. After collecting blood samples, the following indexes were measured. Hp IgG antibodies were measured with a dot enzyme-linked immunoassay; hemoglobin, Hct, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), red blood cell distribution width index (RDW) with automatic Complete Blood Count; SF with an immunoradiometric assay. Stool Hp antigen and occult bleeding were measured with ELISA among individuals who were Hp seropositive. Hp status was defined as positive when both serum and stool antigen tests were positive, Hp status was defined as negative when serum antigen test was negative; 24-hour weighting and recording methods were used to dietary survey for three days in May and December 2001, respectively, dietary intakes including energy, protein and micronutrient were calculated using nursery school nutrition software and evaluated by Chinese Dietary Reference Intakes (DRIs). Mann-Whitney test was used to compare mean ranks of SF in Hp-positive and Hp-negative children. To obtain an adjusted estimate of the impact of Hp infection on SF, a multivariate analysis of covariance was done to evaluate the different level of SF between Hp infected and non-infected status. The relationship between iron deficiency and gender, age, socioeconomic condition, iron intake, and calcium intake was assessed by univariate analysis. An unconditional multivariate logistic regression analysis was also performed. Iron deficiency status was dichotomized and placed as the dependent variable. Hp infection status was incorporated together with possible confounding factors as independent variables in a final logistic regression model. All the data were managed by EPI Info 5.01a and analyzed by SAS (Version 6.12).

Totally 64 children were diagnosed as Hp-positive and 305 as Hp-negative. Mann-Whitney test and multivariate analysis of covariance both showed that SF concentration was significantly lower in Hp infected individuals than non-infected individuals. Adjusted mean level and 95% confidence interval of SF in infected and non-infected children was 23.62 microg/L (7.13 microg/L-78.26 microg/L), 33.48 microg/L (10.28 microg/L-109.06 microg/L), respectively. The relationship between Hp infection and iron deficiency status persisted in logistic regression analysis after adjusting for possible confounding factors (OR: 7.95; 95% CI 2.56 - 24.67).

Iron nutritional status was reduced in Hp infected preschool children. Hp infection appears to be an independent risk factor or an added stressor on iron status among preschool children.