RAGE polymorphisms and oxidative stress levels in Hashimoto's thyroiditis.

BACKGROUND: Polymorphisms of the receptor for advanced glycation end products (RAGE) gene have been studied in various autoimmune disorders, but not in Hashimoto's thyroiditis. Also, increased oxidative stress has been described in patients with Hashimoto's thyroiditis. The aim of this study was to investigate the possible role of two common RAGE polymorphisms (-429T>C, -374T>A) in Hashimoto's thyroiditis; in parallel, we studied oxidative stress levels. MATERIALS AND METHODS: A total of 300 consecutive euthyroid women were examined and classified into three groups: Hashimoto's thyroiditis with treatment (n = 96), Hashimoto's thyroiditis without treatment (n = 109) and controls (n = 95). For a rough evaluation of oxidative stress, total lipid peroxide levels in serum were measured. The -429T>C AluI and -374T>A MfeI polymorphisms of RAGE were studied in genomic DNA. RESULTS: Significant association of the RAGE system with Hashimoto's thyroiditis was found only with regard to the prevalence of the -429T>C, but not with -374T>A polymorphism. The levels of oxidative stress were significantly elevated in Hashimoto's thyroiditis patients under treatment. Further analysis demonstrated that an oxidative stress cut-off value of 590 µmol/L is associated with an increased risk of progression of Hashimoto's thyroiditis from euthyroidism to hypothyroidism; this risk is further increased in carriers of the RAGE -429T>C polymorphism. CONCLUSIONS: Our findings indicate that both examined risk factors may be implicated in the occurrence of Hashimoto's thyroiditis, but this covers only a fraction of the pathophysiology of the disease.

The effect of obesity and dietary habits on oxidative stress in Hashimoto's thyroiditis

Objective: Increased oxidative stress has been described in patients with Hashimoto's thyroiditis (HT). The aim of the present study was to investigate whether high oxidative stress is further influenced by obesity and dietary habits in euthyroid women with HT. Methods: Two hundred eighteen consecutive euthyroid women with HT were studied and separated in two groups; 102 with thyroxine replacement and 114 without. For the evaluation of oxidative stress, total lipid peroxide levels in serum (TOS) were measured and recoded as 'high TOS' vs 'medium/low TOS'. The type of food and consumption frequency were recorded. Two binary variables were considered; normal vs low fruit consumption and daily vs sporadic vegetable consumption. Results: 'High TOS' was more frequent in women under thyroxine replacement (31.4% vs 14.7%, OR = 2.7, 95% CI: 1.4­5.2). The prevalence of 'high TOS' was higher among overweight/obese women compared to women with normal BMI (30.4% vs 12.5%, OR = 3.1, 95% CI: 1.5­6.4). Low fruit consumption was associated with increased 'high TOS' prevalence (30.6% vs 12.9%, OR = 3.0, 95% CI: 1.4­6.2). Sporadic vegetable consumption was associated with increased 'high TOS' prevalence compared to daily consumption (29.9% vs 13.5%, OR = 2.7, 95% CI: 1.3­5.7). The examined risk factors were independent and additive in their effect on TOS. At least three risk factors had to be concomitantly present for the likelihood of 'high TOS' to be significantly elevated. Conclusions: Oxidative stress is increased in women with HT under thyroxine replacement. Nevertheless, normal BMI, daily fruit and vegetable consumption, all contribute in maintaining oxidative stress at low levels.

Phenotypic and metabolic characteristics of women with isolated hyperglycemia in pregnancy-is the time-point important?

OBJECTIVE: To examine the phenotypic and metabolic characteristics of pregnant women with one abnormal glucose value (OAV) in the OGTT compared to normals (N) and to gestational diabetes mellitus (GDM) subjects and also to test if the timing of the observed hyperglycemia is related to any difference in their phenotype. MATERIALS AND METHODS: 7618 pregnant women underwent a 100g OGTT (N = 3813, OAV = 1290, GDM = 2515). The OAV Group was further subdivided according to the time of hyperglycemia: fasting OAV, 1h OAV and 2-3h OAV. Demographic data were recorded and indices of insulin sensitivity and secretion were calculated. RESULTS: The OAV Group presented intermediate values in all demographic parameters and in indices of insulin sensitivity and secretion compared to N and GDM Groups (p < 0.01). Regarding the three OAV subgroups: OAV-Fasting was heavier, had increased HOMA-IR and lower HOMA-B index, than the other two. In contrast, the OAV-1h subgroup had the lower Stumvoll first and second phase indices compared to the others, and also the lowest ISSI (p < 0.01). CONCLUSION: Isolated hyperglycemia appeared to be heterogeneous. Fasting hyperglycemia was mainly characterized by increased hepatic insulin resistance and impaired basal insulin secretion, while OAV at 1h presented increased muscle insulin resistance and diminished stimulated insulin secretion.