Systematic thyroid screening in myotonic dystrophy: link between thyroid volume and insulin resistance

Area of Science:

• Endocrinology
• Neurology
• Oncology

Background:

• Myotonic dystrophy (DM1) is a neuromuscular disease linked to DMPK gene mutations.
• DM1 is associated with endocrine disorders and an increased risk of cancer.
• Routine endocrine evaluation, including thyroid ultrasound (US), was performed on DM1 patients.

Purpose of the Study:

• To determine the prevalence of US thyroid abnormalities in DM1 patients.
• To identify the causes of these thyroid abnormalities.
• To assess the diagnostic yield of US in detecting thyroid cancer in DM1.

Main Methods:

• A cohort of 115 genetically confirmed DM1 patients underwent thyroid US.
• Thyroid volume, nodules, and goiters were assessed.
• Fine-needle aspiration cytology and thyroidectomy were performed when indicated, guided by the Thyroid Imaging Reporting and Data System (TIRADS) classification.

Main Results:

• US goiter was found in 38.3% and US nodules in 60.9% of patients.
• Papillary thyroid carcinoma (PTC) was diagnosed in 7.9% of patients (9 cases), with two-thirds being micro-PTCs.
• Thyroid volume correlated positively with BMI and parity, and inversely with TSH and vitamin D levels.

Conclusions:

• The study identified a high frequency of US thyroid abnormalities in DM1 patients.
• While PTCs were detected, many were small and low-risk.
• Targeted thyroid US screening in DM1 patients with clinical abnormalities or high BMI is recommended over systematic screening.