Association between idiopathic retroperitoneal fibrosis and autoimmune thyroiditis: a case-control study

Area of Science:

• Endocrinology
• Autoimmune Diseases
• Rare Diseases

Background:

• Idiopathic retroperitoneal fibrosis (IRF) is a rare condition often linked to autoimmune disorders.
• The association between IRF and Hashimoto's thyroiditis (HT) remains poorly understood, with limited evidence from case reports.
• This study aimed to determine the prevalence of HT in a large cohort of IRF patients compared to matched controls.

Purpose of the Study:

• To investigate the prevalence of Hashimoto's thyroiditis (HT) in patients with idiopathic retroperitoneal fibrosis (IRF).
• To assess the association between IRF and autoimmune thyroiditis using serological and imaging markers.
• To evaluate the long-term thyroid function in IRF patients.

Main Methods:

• Cross-sectional study of 73 new-onset IRF patients and 71 controls.
• Evaluation of anti-thyroperoxidase antibodies (AbTPO), free thyroxine (FT4), and thyroid-stimulating hormone (TSH).
• Thyroid ultrasound (US), fine-needle aspiration biopsy (FNAB), and thyroidectomy histology were used for diagnosis.

Main Results:

• IRF patients showed a higher prevalence of AbTPO positivity and US findings suggestive of autoimmune thyroiditis (US-AIT) compared to controls.
• Logistic regression revealed a significantly higher risk of AbTPO-diagnosed HT (OR=3.56) and US-AIT (OR=4.74) in IRF patients.
• At follow-up, 25% of IRF patients required l-thyroxine treatment, versus 3% of controls.

Conclusions:

• Idiopathic retroperitoneal fibrosis (IRF) is associated with an increased risk of Hashimoto's thyroiditis (HT).
• Routine thyroid function monitoring is crucial for patients diagnosed with IRF.
• Autoimmune thyroiditis may be a significant comorbidity in IRF patients.