Conditions Besides Hypermobile Ehlers-Danlos Syndrome Associated with Thyroid Disorders
Several autoimmune conditions are strongly associated with thyroid disorders, with autoimmune hepatitis, systemic lupus erythematosus, and Sjögren's syndrome showing the most significant connections.
Primary Autoimmune Conditions Associated with Thyroid Disease
Autoimmune Hepatitis (AIH)
- Thyroid disorders are the most common concurrent autoimmune disease in AIH patients, affecting approximately 10.5% of cases 1
- Specifically:
- Hashimoto's thyroiditis accounts for 10.2-14.1% of all concomitant autoimmune diseases in AIH
- Graves' disease occurs in approximately 3-6% of AIH patients 1
- Patients with AIH accompanied by autoimmune thyroid disease (AITD) typically present with elevated IgG levels 1
Systemic Lupus Erythematosus (SLE)
- Thyroid disorders occur in approximately 50% of SLE patients, significantly higher than in other autoimmune conditions 2
- Distribution of thyroid dysfunction in SLE:
- 20% have euthyroid sick syndrome
- 20% have hypothyroidism (10% subclinical, 10% biochemical)
- 10% have hyperthyroidism (5% subclinical, 5% biochemical) 2
- Thyroid autoantibodies often precede clinical thyroid disease in 70% of SLE patients 3
- SLE patients should be routinely screened for thyroid dysfunction as symptoms can overlap 3
Sjögren's Syndrome
- Autoimmune thyroiditis is nine times more frequent in patients with primary Sjögren's syndrome 4
- Subclinical hypothyroidism is the most common thyroid hormonal pattern in Sjögren's syndrome 4
- Shared antigens between thyroid and salivary glands may explain the strong association 4
- Patients with Sjögren's syndrome have a 44-fold increased risk for parotid lymphoma, which is also associated with thyroid disorders 4
Rheumatoid Arthritis (RA)
- Thyroid disorders occur in approximately 15% of RA patients 2
- Specifically:
- 10% have subclinical hypothyroidism
- 5% have subclinical hyperthyroidism 2
- Anti-thyroglobulin antibodies (ATGAb) are found in 30% of RA patients, at higher titers than in the general population 2
Other Conditions with Thyroid Associations
Hepatitis C Virus (HCV) Infection
- HCV infection is associated with autoimmune thyroid disorders, particularly in patients with mixed cryoglobulinemia 1
- Higher prevalence of thyroid disorders in HCV patients compared to controls 1
- Risk factors for developing thyroid autoimmunity in HCV patients include:
- Female gender
- Borderline high initial TSH
- Anti-thyroid peroxidase antibody (AbTPO) positivity
- Hypoechoic and small thyroid 1
Down Syndrome
- People with Down syndrome are at higher risk for thyroid dysfunction 1
- Evaluating hypothyroidism symptoms can be challenging as some clinical features overlap with Down syndrome (e.g., slow speech, thick tongue, slow mentation) 1
Clinical Implications and Management
- Patients with any of these autoimmune conditions should be screened for thyroid dysfunction
- For HCV patients with risk factors, annual monitoring is recommended:
- Free thyroxine (FT4)
- TSH
- Anti-thyroglobulin antibodies (AbTg)
- Anti-thyroid peroxidase antibodies (AbTPO)
- Thyroid ultrasonography 1
- In patients with thyroid nodules >1cm or with suspected malignancy, fine-needle aspiration should be performed 1
Pitfalls and Caveats
- Symptoms of thyroid disease may overlap with symptoms of the primary autoimmune condition, leading to missed diagnoses
- Subclinical thyroid disease is much more common than overt disease in these populations 1
- Thyroid autoantibodies often precede clinical disease and should prompt closer monitoring 3
- Severe non-thyroid illness can lead to false positive TSH test results, complicating diagnosis 1
While hypermobile Ehlers-Danlos Syndrome has been associated with thyroid disorders, these other autoimmune conditions demonstrate even stronger and more well-documented connections to thyroid dysfunction, particularly autoimmune hepatitis, SLE, and Sjögren's syndrome.