The Association between Helicobacter pylori and Graves ' Disease

Patients and Methods: This case control study included 43 patients with GD and a control group of 47 healthy volunteers. Hormonal diagnosis of GD was achieved by decreased level of thyroid stimulating hormone (TSH) and elevated levels of triiodothyronine (FT3) and free thyroxine (FT4) and serological diagnosis was achieved by positive titers of autoantibodies against thyroglobulin (TG Abs), thyroid peroxidase (TPO Abs) and thyrotropin receptor (TR Abs). H. pylori infection was diagnosed by detecting H. pylori antigens in stool using an amplified enzyme immunoassay (amplified EIA). The antibodies against Cytotoxin-associated gene A (Cag-A) were assessed in serum samples using the enzyme-linked immunosorbent assay method (ELISA). The results were statistically analyzed using Fisher's test and the respective Odd's ratio (OR).


INTRODUCTION
Helicobacter pylori (H.pylori) is a worldwide chronic infection [1,2].It is a Gram -negative spiral pathogen that inhabits the gastric mucosa causing multiple gastric diseases such as chronic gastritis, peptic ulcers, and gastric malignancies [3,4].It was also incriminated in both organ specific and non-organ specific autoimmune disease [5].H. pylori was also involved in many extra gastric diseases such as nonalcoholic fatty liver diseases and metabolic syndrome [6,7].Many available data links autoimmune thyroid diseases (ATD)-particularly Graves' disease (GD)with H. pylori infection [8].A strong association between thyroid auto-antibodies and immunoglobulin G (IgG) anti-H.pylori antibodies was reported.Radical treatment of H. pylori infection was found to be associated with a gradual drop in the levels of thyroid autoantibodies, however these data are still controversial This work aims at investigating the relationship between GD and H. pylori infection and whether there is any association in between.GD patients were selected based on their positive hormonal hyperthyroidism profile -including suppressed thyroid stimulating hormone (TSH), elevated free tri-iodothyronine (FT3), elevated free thyroxine (FT4) and positive titers of TPO Abs, TG Abs and TR Abs.They were measured by electrochemiluminescence immunoassay (ECLIA) on cobas immunoassay analyzers.Anti TG titer above 50 ng/ml and anti TPO above 200 IU/ml were considered positive.The control group individuals were confirmed to have normal TSH, FT3 and FT4, and to be free from autoantibodies against TPO, TG and TR.Also, thyroid ultrasound was done to assess the presence of goiter and to exclude thyroid nodules.Both groups were subjected to thorough history taking and clinical examination, then they underwent the following:

PATIENTS AND METHODS
 H. pylori antigens were detected in fresh stool samples by amplified enzyme immunoassay (Amplified IDEIA H. pylori StAR, Oxoid, United Kingdom).Positive results were confirmed for the presence of H. pylori with an absorbance value >0.150 using a dual wavelength (450/ 620 to 650 nanometers).

Statistical analysis:
The statistical analysis of results was carried out by an experienced epidemiologist.It was achieved using the SPSS version 19 considering P value <0.05 as statistically significant.The Chi-square or Fisher exact test were used to assess differences in proportions among categorical data.The independent impact of H. pylori on GD was assessed by multivariate analysis.On univariate analysis, variables with a P value of <0.2 were included in the multivariate analysis using Logistic regression for this purpose.Odds ratios (OR) with a confidence interval (CI) of 95% were reported.Median and interquartile range (IQR) were used to represent continuous variables.

RESULTS
A collaborate work was conducted over one year between Tropical Medicine Department and Internal Medicine Department, Faculty of Medicine Zagazig University.Forty-three GD patients were included in the study along with 47 healthy control individuals.
The study groups were classified into age and sex subgroups (range= 18-65 years).No statistically significant difference was found between both groups regarding age or sex (Table 1).
The mean, median and range of the body mass index showed no significant differences between the GD group and the control group (Table 2).
The prevalence of H. pylori +ve stool Ag was found to be more among GD patients' group (46.5%) than the control group (42.6%), but the difference was statistically insignificant.The prevalence of Cag A antibodies among the study groups was found to be more among H. pylori +ve stool Ag of the control group (30%) than the H. pylori +ve stool Ag of GD patients' group (20%), but the difference was statistically insignificant (Table 3).
H. pylori was more prevalent among the age subgroup of 40-59 years of both GD patients and the control group but the difference was statistically insignificant (Table 4).
The prevalence of H. pylori was not associatedwith GD (OR 1.02, 95% CI 0.57-1.83,P=0.95), but the family thyroid malfunction was found to be a risk factor independently associated with GD (OR =3.93, 95% CI was 1.86-618, and P < 0.001) (Table 5).This study showed that the prevalence of H. pylori was more among GD patients' group than the control group, but the difference was statistically insignificant.Interestingly, the prevalence of Cag A antibodies was even found to be more among the control group than the GD group, but the difference was statistically non-significant.These results agree with that of Tomasi et al.

Conclusion:
There is no association between H. pylori infection and Graves' Disease.

Table ( 1
): Classification of patients and control groups according to age and sex.

Table ( 2
): Comparison between the two study groups regarding the body-mass index (BMI).

Table ( 4
): Comparison between different age subgroups regarding the prevalence of H. pylori infection

Table ( 5
): Multivariate analysis of risk factors associated with GD.

29-32].
This can be explained by sharing the same genetic or environmental factors by the family members.There was no significant difference in H. pylori prevalence among the different age subgroups of both GD and control groups, coinciding with the study result of Haim et al who found no associated between age and H. pylori prevalence [33].However, these results do not agree with some authors [34-36] who mentioned that H. pylori infection is usually acquired during childhood and increases with age, with rare possibility to attract new infection in adulthood.Again, this controversy can be explained by the different genetic and environmental factors under which the different studies were conducted.