Endocrine Abstracts

Context: Graves’ disease (GD) is the most common cause of hyperthyroidism, usually affecting women.

Objective: To asses the thyroid function and volume in GD patients treated with anti-thyroid drugs (ATD) in different regimens.

Patients and Methods: The study included 128 adult patients (104 females (F), 24 males (M)) with newly diagnosed or relapsed GD treated medically. Patients were consecutively admitted to a tertiary endocrinology center. Two visits were recorded at a time interval of 2-6 months. Patients with a medical history of radioiodine therapy, those who underwent thyroid surgery, pregnant women and those who were not compliant with medical therapy were excluded. The group was divided into two subgroups according to the ATD regimen used: block-replace (B) and titration (T) regimen. Thyroid hormone levels (free thyroxine (fT₄) and total triiodothyronine (TT3)), thyroid stimulating hormone (TSH) and TSH receptor antibodies (TRAb), ATD and levothyroxine (LT₄) doses used were registered. Each patient underwent thyroid ultrasound. Thyroid volume was expressed in cm³ and calculated with the formula: sum of anterior-posterior*transverse* longitudinal diameters*0.5233 of each thyroid lobe.

Results: Subgroup B enrolled 53 patients (43 F, 10 M), mean aged 50.4±11.8 year-old (y.o) and subgroup T enrolled 75 patients (61 F, 14 M), mean aged 46±15.2 y.o., P = 0.06. During medical therapy the levels of TSH and fT₄ were stable in both subgroups. Also, during medical therapy TRAb levels and thyroid volume decreased in both subgroups but not statistically significant. TRAb levels were statistically significant lower in subgroup B than in subgroup T during both visits: 8.3±10.8 UI/l versus 14.6±13.5 UI/l (visit 1) and 6.7±10.1 UI/l versus 14.1±14.2 UI/l (visit 2) respectively, P = 0.01. TRAb levels decreased by 1.51 UI/l 95% CI (-3.23; 6.24) in subgroup B and by 0.52 UI/l 95% CI (-5.51; 6.55) in subgroup T. Thyroid volume was higher in subgroup B than in subgroup T: 25.3±16.7 cm³ versus 15.5±15.9 cm³ (visit 1) and 23.8±19.5 cm³ versus 11.2±20.5 cm³ (visit 2) respectively, P = 0.002. Thyroid volume decreased by 1.48 cm³ 95% CI (-5.84; 8.79) in subgroup B and by 4.23 cm³ 95% CI (-2.46; 10.99) subgroup T, respectively. The ATD used was MMI, with lower doses in subgroup B than in subgroup T: 12.21±6.2 mg/d versus 19.8±15 mg/d (visit 1), P = 0.001 and 12.09±7.63 mg/d versus 15.42±8.61 mg/d (visit 2), P = 0.04. The MMI and LT₄ doses used in block and replace regimen were similar during both visits, while in the titration regimen MMI doses were statistically significant lower in the second visit than in the first visit, P = 0.03. These results could be explained by the fact that in subgroup B were enrolled more patients with relapsed GD than in subgroup T: 67.92% (36/53) patients versus 38.66% (29/75) patients, P = 0.001.

Conclusion: Block replace regimen could be suitable for complicated GD with benefits for both TRAb levels and thyroid volume.