Conversion to Graves disease from Hashimoto thyroiditis: a study of 24 patients

ABSTRACT Objective: The conversion of Hashimoto's thyroiditis (HT) to hyperthyroidism due to thyrotropin receptor antibodies is intriguing and considered rare. The contribution of TSH receptor blocking antibodies (TRAb), which may be stimulators (TSAb) or blockers (TBAb), is suspected. We describe clinical and biological variables in a series of patients switching from Hashimoto's thyroiditis to Grave's disease. Subjects and methods: Retrospective case study of 24 patients with Hashimoto's thyroiditis followed during 48 ± 36 months that developed later Graves' disease (GD). These variables were analysed in the hypo and hyperthyroid phase: age, sex, initial TSH, free triiodothyronine (fT3), free thyroxine (fT4), anti-TPO, TBII antibodies, parietal cell autoantibodies, time between hypo and hyperthyroidism, thyroid volume and levothyroxine doses (LT). Results: In HT, mean TSH was 9.4 ± 26.1 UI/L and levothyroxine treatment was 66.2 ± 30.8 µg/day. The switch to GD was observed 38 ± 45 months after HT diagnosis. As expected, we found significant differences on TSH, FT3, FT4 and TBAb levels. Three out of 14 patients had parietal cell autoantibodies. In two of these three cases there was an Helicobacter pylori infection. There were no significant differences between HT and GD groups with respect to thyroid volume. Conclusions: To our knowledge, large series documenting the conversion of HT to GD are scarce. Although rare, this phenomenon should not be misdiagnosed. Suspicion should be raised whenever thyroxine posology must be tapered down during the follow-up of HT patients. Further immunological and genetic studies are needed to explain this unusual autoimmune change.

TSH-receptor antibodies may prevent bone loss in pre- and postmenopausal women with Graves' disease and Graves' orbitopathy

ABSTRACT Objective Thyrotoxicosis is established risk factor for osteoporosis due to increased bone turnover. Glucocorticoids often administered for Graves' orbitopathy (GO) have additional negative effect on bone mineral density (BMD). Our aim was to examine the influence of thyroid hormones, TSH, TSH-receptor antibodies (TRAb) and glucocorticoid treatment on bone in women with Graves' thyrotoxicosis and Graves' orbitopathy (GO). Subjects and methods Forty seven women with Graves' disease, mean age 55.6 ± 12.8 (23 women with thyrotoxicosis and 24 hyperthyroid with concomitant GO and glucocorticoid therapy) and 40 age-matched healthy female controls were enrolled in the study. We analyzed clinical features, TSH, FT4, FT3, TRAb, TPO antibodies. BMD of lumbar spine and hip was measured by DEXA and 10-year fracture risk was calculated with FRAX tool. Results The study showed significantly lower spine and femoral BMD (g/cm2) in patients with and without GO compared to controls, as well as significantly higher fracture risk. Comparison between hyperthyroid patients without and with orbitopathy found out significantly lower spine BMD in the first group (p = 0.0049). Negative correlations between FT3 and femoral neck BMD (p = 0.0001), between FT4 and BMD (p = 0.049) and positive between TSH and BMD (p = 0.0001), TRAb and BMD (p = 0.026) were observed. Fracture risk for major fractures and TRAb were negatively associated (p = 0.05). We found negative correlation of BMD to duration of thyrotoxicosis and cumulative steroid dose. Conclusions Our results confirm the negative effect of hyperthyroid status on BMD. TRAb, often in high titers in patients with GO, may have protective role for the bone, but further research is needed.

TSHR gene intron 1 region polymorphism and its relationship with Graves' disease / 中华内分泌代谢杂志

Objective To investigate the association between the six single nucleotide polymorphisms ( SNP),named as rs179247,rsl2101261,rs2284722,rs4903964,rs2300525,rsl7111394 in the intron 1 of thyroid stimulating hormone receptor gene (TSHR) and Graves' disease (GD).MethodsThe genotypes of the six SNPs were genotyped by Taqman probe technique on Fluidigm EP1 platform in 618 GD patients and 646 control subjects.Meanwhile,TSH receptor antibodies (TRAb) of the patients were determined.ResultsAmong the six SNPs,five S NPs were strongly associated with GD,with the most signals at rs179247_G,rs12101261_C,rs4903964 _G (P=2.85×10-10,OR=1.73,95％CI1.46-2.05;P=1.74×10-10,OR=1.73,95％CI 1.46-2.05;P=2.24×10-10,OR=1.69,95％ CI 1.44-1.99 ).The results of logistic regression analysis indicated that rs12101261 and rs4903964 were main susceptibility loci of GD in the intron 1 of TSHR.rs179247_G,rs1210126 1_C,and rs4903964_G were associated with subset of the GD patients with positive TRAb (P=4.24× 10-13,p=5.48× 10-13,P =3.89×10-12 ).Conclusionrs179247,rs12101261,and rs4903964 in TSHR intron 1 were significantly associated with GD in the Chinese Han population from Bengbu city.rs12101261 and rs4903964 were the major susceptibility SNPs associated with GD.TSHR gene may play a main role of susceptibility gene in the subset of GD patients with persistent positive TRAb.

Association of TSHR gene intron 1 polymorphisms with Graves′ disease / 中华内分泌代谢杂志

Objective To investigate the association between polymorphisms of thyroid-stimulating hormone receptor(TSHR)gene intron 1(rs179247, rs12101261)and Graves′ disease(GD)in the China Han population from Xuzhou city, Jiangsu Province. Methods Total 1 066 GD patients and 1 107 control subjects were recruited for genotyping by Taqman probe technique on Fluidigm EP1 platform. Meanwhile, serum concentrations of thyroid hormone and TSH receptor antibodies(TRAb)were determined. Results The rs179247_A, rs12101261_T were significantly associated with GD risk(OR=1.35, 95%CI 1.19-1.54, P=5.92×10-6; OR=1.32, 95%CI 1.16-1.50, P=2.22×10-5). Logistic regression identified that rs179247 was an independent susceptibility locus of GD. Serum TRAb concentration showed a significant difference(P=0.015)among rs179247_AA, AG, and GG genotypes. Conclusion rs179247 and rs12101261 in TSHR intron 1 are both associated with GD, and rs179247 may contribute risk to GD independently. The polymorphism is associated with TRAb, but not with serum concentration of thyroid hormones, age of onset, diffused thyroid goiter, ophthalmic signs, and relapse.