Objective: To measure thyroid cell proliferation in patients with Graves' disease (GD) before and during treatment with antithyroid drugs.
Study design: Patients were assessed by fine needle aspiration biopsy before (n = 20) and after 4 (n = 19) and 12 months of treatment (n = 15) with propylthiouracil or methimazole. Cell proliferation index (CPI) was estimated by immunocytochemistry using MIB-1. CPI was studied in relation to the cytologic parameters of the smears; clinical parameters, such as Wayne's Clinical Index (WCI) and time without treatment; laboratory parameters, such as 131I uptake and dosage of serum free thyroxin and thyroid-stimulating hormone; and thyroid ultrasound.
Results: CPI varied from 0.00% to 25.00% before treatment, 0.00% to 23.00% at 4 months and 0.00% to 14.84% at 12 months. CPI median values were 6.50%, 4.30% and 3.30%, respectively (before and after 4 months and 12 months of treatment). CPI had a positive correlation with WCI and FT4 at 12 months of treatment.
Conclusion: Thyroid CPI in GD varies from case to case. However, due to its decreasing pattern during follow-up and its positive correlation with thyrotoxicosis severity, CPI may indicate the functional status of the gland and contribute to a better understanding of GD.