The Study On Relationship Between Serum Iron Of Middle School Students And Primary Hypertension

IntroductionEssential hypertension (EHT) is a common cardiovascular disease among adults. Recently, followed by studying EHT on the adults more deeply, more and more people pay attention to EHT of children and adolescent .Some studies on the reason for EHT of children have been reported which come from heredity and environment. The research was centering on the adults crowd of the relation between EHT and trace elements , such as serum sodium, kalium, calcium, magnesium, zinc, etc.There are few studies on the relation between serum iron (SI) and EHT, moreover the conclusion was not consistent and lacked of the large scale reports . Therefore, this study chose a lot of middle school students as object who came from the place with high incidence rate of EHT that we had confirmed, so that we can understand distribution condition of children blood pressure at place with high incidence rate of EHT and explore the relation between SI and children EHT, then on the base of which we can put forward the prevention and cure measure.Subjects and Methods1. The selection method and standard of objectsUsing the method of clustering multistage sampling method, 5 countrysides were randomly selected from Eeast, South, West, North, Middle in ZhanWu County, LiaoNing Province. All the primary school students in the selected 5 countrysides were investigated. Other conditions being able to induce serum ironincrease or decrease unrelated to body iron stores such as acute hepatitis or malignancy etc. were excluded. And secondary hypertension was excluded also. There were 1640 students being selected at last.2. The contents of epidemiological survey and detection index(1) Questionnaires were filled by means of inquiring and measurement in sites. The contents of survey included: general characteristics, alcohol intake, smoking habits, family history of hypertension, previous disease history and so on, measurement of the blood pressure, body height and weight, etc.(2) Five milliliters blood samples were drawn from an antecubital vein after an overnight fast. After centrifugation, the serum fraction was removed and frozen in aliquots at -70℃ until assayed. The serum was used for the measure of Serum Iron ( SI) and other hemal - biochemistry assay related to EHT.3. Diagnosis standard and chemical measurementsThe diagnosis standard of EHT; According to 1987 American Controlling Blood Pressure Work Group propose the diagnosis standard, 13-15 years old; hypertension Child was defined as a systolic blood pressure (SBP) ≥136mmHg And/or a diastolic blood pressure ( DBP) ≥ 86mmHg. The measurement of blood pressure should be carried out according to the unified standard under standard conditions.SI, cholesterol ( CHOL ) , triglyceride ( TG ) , high density lipoprotein (HDL) , low density lipoprotein(LDL) , serum sodium, serum potassium, serum calcium were measured by automatic biochemistry analyzer 7150 ( HITACHI , Japan) , the blood sugar was measured by blood sugar analyzer (Johnson & Johnson, America).4. Statistical methodsA database was created after quality examination of data. Statistical analysis of dichotomous variables was by the chi - square test. Student's t - test was used to assess differences between groups for two continuous variables. Kruskal - wallis test was used to assess differences between groups for multiple continuous variables allowing for unequal variances. Multiple Logistic regression was used when evaluating the effect of a continuous or categorical covariates on a dichotomous outcome. A 2 -sided value of P <0. 05 was regarded as statisticallysignificant. The software used was SPSS10. 0.Result1. The distribution character of primary school students'blood pressure 1. 1 The distribution character of blood pressure between sex The level of both SBP and DBP of the girl group was higher than that of the boy group. There was statistical difference(t = 5. 807,p <0. 01 )of DBP between sex, but not SBP( t = 1.805,p<0. 071).1. 2 The distribution character of blood pressure among different age groups There was statistical difference(F = 9. 879,p = 0. 000) of SBP. To compare with each other, there was statistical difference ( F = 2. 58, p = 0. 011) of SBP between 13years and 15years, likewise between 14years and 15years(F =2. 83, p =0.000), but not between 13years and 14years. There was statistical difference ( F=3. 047, p = 0. 048 ) of DBP. To compare with each other, there was statistical difference ( F = 1. 25, p =0. 017) of DBP between 14years and 15years, but not between 13years and 14years, nor between 13years and 15years.1. 3 The distribution character of blood pressure among different age groups between sexThere was statistical difference( boy: F = 5. 546, p = 0. 004; girl; F = 4. 532,p = 0. 011) of SBP among different age groups between sex. To compare with each other of the boy group, there was statistical difference(p =0.001)between 14years and 15years, but not between 13years and 14years, nor between 13years and 15years. Of the girl group, there was statistical difference(p =0. 022, p =0.013)between 13years and 15years , likewise 14years and 15years, but not between 13years and 14years. Of the boy group, there was statistical difference (F = 5. 607 , p = 0.004 ) of DBP, but not of the girl group. To compare with each other, there was statistical difference (p =0. 001 ) of DBP between boys of 14years and 15years.2. The distribution character of Serum Iron between case and control2. 1 The level of Serum Iron between sex in EHT patients and control group There was no statistical difference( 15. 64 ± 6. 64,14. 85 ± 6.13, t = 1. 348,p=0. 178) between EHT patients and control group. To the boys level of SI of the EHT group, SBP group and DBP group were all higher than that of control group(t=3.630,p=0.000,t = 1.965,p=0.05,t=3.607,p=0.000). To the girls there was no significant difference among all the groups.2.2 The level of Serum Iron among different age groups in EHT patients and control groupThere was no statistical difference between EHT patients and control group among different age groups. The same to the SBP group and the DBP group. But the level of Serum Iron of EHT patients, the SBP group and the DBP group were both higher than that of control group.There was no statistical difference among different age groups of EHT patients , the SBP group and the DBP group.3. The association between the different level of Serum Iron and EHTThe upper interval of normal level of SI was 21. 8, then defined high level of Serum Iron with higher than 21. 8. The result was that high level of Serum I-ron was risk factors of EHT( OR = 1.733 ,95% CI: 1.081 ~ 2.777 ). But there was no statistical difference in single SBP and DBP group.3.1 The relation of different level of Serum Iron to EHT between sexTo boy group, high level of SI was risk factors of EHT, single SBP and DBP group(OR=3.813,95%CI:2.028~7.172, OR =3. 669,95%CI:1.585 -8.492, OR = 3. 383,95% CI: 1.637 -6.994). To girl group, there was no relationship between high level of Serum Iron and EHT.3.2 The association between the different level of Serum Iron and EHT a-mong different age groupsFor 13 -year students, high level of SI was risk factors of EHT (OR =6. 000,95% CI :1. 009 -35. 679). For 14 -year students, high level of SI was risk factors of EHT and single SBP group( OR = 2. 767,95% CI: 1. 140 ~ 6.715 ; OR=5.749,95%CI:1.627~20.314).DiscussionMany study data showed that blood pressure of children increase with age, while most experts nowadays consider that this tendency is related with growthand development. This study results show that blood pressure of middle school students also increase with growth. Furthermore the level of SBP and DSP of school girls are higher than boys constantly and both do not have crossing. This result is similar to distribution condition of children in countryside area of Beipi-ao , IiaoNing province (west) , but which is somewhat different from other data. The data of National Health Examination Survey (NHES) showed that average SBP level of boys age from 13-17 was higher than school girls and there was no difference of DBP between sex. The surveys in many countries almost have this phenomenon. In 1985 the result of investigation data about constitution of China students approximates to NHES.This investigation detects 122 cases of hypertension in total, in which morbidity rate is 7. 44% . This result is slightly lower than that of children of Beijing city with the same diagnosis standard by LiJing, et al.As we know, there are too many risk factors, such as overweight and obesity, natrium in food, alcohol intake and heredity, etc. but these can not explain the mechanism of primary hypertension very well. There are many latent and unknown factors, which should be considered. Few studies show us the relation between iron with hypertension. But many results imply the certain relation of i-ron with the increasing of blood pressure. This study finds that there exists significant difference of SI level between group of primary hypertension and control group of middle school students, and SI level of hypertension group is higher than normal group. Among the results there exist significant differences between SI level of hypertension, high SBP, high DBP groups and that of control group of boys, all are higher than control group. This result suggests that high level SI of middle school students is probably risk factor of primary hypertension, which is similar to result being studied by Piperno, et al in 2002.SI was used as an indicator of the level of body iron stores in our study. We excluded other conditions able to induce serum iron change unrelated to body i-ron stores such as acute hepatitis or malignancy etc, and blood samples were drawn after an overnight fast in order to avoid dietetic effect, because SI was sensitive to inflammation and other various disease processes for the reason that SI as a biochemical indicator of iron status of body in this study was compara-...