Summary
This study examined whether symptoms of Grave’s opthalmopathy (GO) were associated with patients’ levels of thyroid antibodies and/or levels of thyroid hormones. The hypothesis is that patients with high antibody levels and/or high thyroid hormone levels would have more severe symptoms of GO.
The authors did this study by looking back through the medical records of patients at their hospital. In total, they found records from 182 Grave’s patients who developed GO. Of these patients, when the GO developed, 143 were hyperthyroid (high levels of thyroid hormones), 28 were euthyroid (normal levels of thyroid hormones), and 11 were hypothyroid (low levels).
The sex, age, and smoking status of the patients were not correlated with their development of GO. This is interesting because other articles have shown that smoking greatly increases the risk of GO.
Thyroid hormones: Thyroid hormone levels were important in the development and the severity of GO. Patients with low or normal thyroid hormone levels (hypothyroid and euthyroid patients) had less severe GO than hyperthyroid patients did. The amount of steroid given to treat the GO was the same for everyone, but the need for irradiation therapy was less in the hypothyroid and euthyroid groups. This shows the importance of getting the thyroid hormone levels down to decrease the severity of GO.
Antibodies: The authors looked at two antibodies associated with Grave’s Disease. Normally people produce antibodies to foreign “germs” as part of the body’s immune defenses. Sometimes however, people produce antibodies against their own body, leading to an autoimmune (self-immune) problem. In many people with Grave’s Disease, their body produces antibodies that fight the thyroid gland. Two of these antibodies include TRAb (thyroid antibody) and TPOAb (thyroid peroxidase antibody). The authors looked at the level of these two antibodies in the patients before, during, and after the patients developed GO.
TRAb levels were higher in hyperthyroid patients than in euthyroid or hypothyroid patients. TPOAb levels didn’t differ between the groups. After 6 months of treatment for GO, only 69% of the euthyroid and hypothyroid patients still had elevated TRAb levels, but 94% of the hyperthyroid patients still had elevated levels. Also, 25% of the euthyroid and hypothyroid patients had no TRAb or TPOAb, while only 5% of the hyperthyroid patients didn’t have these antibodies. It’s hard to know in studies like this what is the cause and what is the effect. Did patients whose Grave’s Disease was naturally going away have less GO because of that? Or did treatment reduce the GO? It is clearly possible to have Grave’s Disease and/or GO without antibodies against the thyroid. Perhaps there are other antibodies being produced that we don’t have tests for yet. The bottom line is that people with lower thyroid hormone often also had lower antibody levels. However, whether that is a cause or a result of their treatment is unclear.
Some people developed GO before they got diagnosed with Grave’s. In fact, 25% of people with GO developed thyroid problems within 4 years. The authors suggest that thyroid levels be checked regularly in people with GO, even if their thyroid levels are currently normal.
Bottom line: patients with well-managed thyroid levels had less severe GO and lower thyroid antibody levels.
Reference
A K Eckstein et al., “Euthyroid and primarily hypothyroid patients develop milder and significantly more asymmetrical Graves ophthalmopathy,” British Journal of Ophthalmology 93: (2009): 1052 -1056.
Abstract:
Retrospective, observational study to compare clinical symptoms and TSH-receptor antibodies (TRAb) in Graves ophthalmopathy (GO) in euthyroid and primarily hypothyroid patients to those in hyperthyroid patients.Methods: Clinical symptoms (NOSPECS (severity) and CAS (activity) score), prevalence and levels of thyroid specific antibodies and the course of the disease were evaluated in 143 primarily hyperthyroid, 28 primarily euthyroid and 11 primarily hypothyroid patients with GO.Results: Patients with euthyroid/hypothyroid GO developed significantly less severe GO symptoms (NOSPECS score 4.4 vs 5.7; p = 0.03), less active GO (CAS score 3.9 vs 5.2; p = 0.002) and more asymmetrical disease (proptosis side difference: 1.9 mm vs 1.0 mm (p = 0.01); side difference of ⩾3 mm: 23% vs 4.8%) than hyperthyroid patients. TRAb levels 6 months after GO onset were significantly lower (2.2 IU/l, p = 0.02) in euthyroid/hypothyroid than in hyperthyroid patients (8.6 IU/l), as was the prevalence of both TRAb and thyroid peroxidase antibodies (75% vs 94.6%, p = 0.0008).Conclusions: The knowledge about the phenotype of GO in primarily euthyroid and hypothyroid patients is helpful for differential diagnosis and patient consultation. TRAb titres are very low in these patients, and the availability of a sensitive assay technique is therefore an important diagnostic tool in euthyroid and hypothyroid patients.
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