Changes in serum thyroglobulin and antithyroglobulin shortly following high-intensity focused ablation of benign thyroid nodules in patients with positive antithyroglobulin status

Figures & data

Figure 1. The boxplots for serum thyroglobulin (Tg in ng/mL) at baseline and on day 4 in patients with or without anti-Tg autoantibody.

Figure 2. The boxplots for serum anti-thyroglobulin (anti-Tg) (in ng/mL) at baseline and on day 4 in patients with or without anti-Tg autoantiboody.

Figure 3. A scatterplot showing the correlation between percentage anti-Tg drop on day 4 and 6-month nodule shrinkage (VRR).

Figure 4. A patient with positive anti-thyroglobulin autoantibody status.

Table 1. A comparison of baseline characteristics between patients with positive (> 99 IU/mL) anti-thyroglobulin antibodies (Group I) and patients with negative (≤ 99 IU/mL) antithyroglobulin antibodies (Group II).

Variable	Group I (n = 85)	Group II (n = 191)	p-value
Age at treatment (years)	43.19 ± 11.51	49.37 ± 11.61	.438
Sex (male:female)	9 (10.6) : 76 (89.4)	32 (16.8) : 159 (83.2)	.204
WHO nodule grade on presentation			.278
Grade 1A (palpable but not visible when neck is extended)	5 (5.9)	9 (4.7)
Grade 1B (palpable and visible when neck extended)	29 (34.1)	32 (16.8)
Grade 2 (visible when neck is in the normal position)	31 (36.5)	94 (49.2)
Grade 3 (visible from distance)	20 (23.5)	56 (29.3)
Body mass index (kg/m^2)	23.25 ± 3.99	23.57 ± 5.12	.837
Serum TSH (mIU/L)	1.69 ± 2.47	1.41 ± 2.14	.891
Serum-free T4 (pmol/L)	16.52 ± 4.40	16.63 ± 2.89	.482
Serum Tg (ng/mL)	220.81 ± 808.38	331.79 ± 883.59	<.001
Anti-Tg autoantibody (IU/mL)	547.89 ± 865.25	≤ 99.0 ± 0.0	<.001
Anti-TPO autoantibody (IU/mL)	3259.78 ± 3501.16	281.23 ± 764.68	<.001
Dimensions of the nodule on US
Width (cm)	3.17 ± 1.61	2.96 ± 1.23	.696
Length (cm)	4.25 ± 2.18	3.88 ± 1.36	.388
Depth (cm)	2.63 ± 1.40	2.37 ± 1.01	.648
Volume (mL)^a	27.17 ± 51.99	21.50 ± 46.71	.484
Distance from skin to centre (mm)	12.6 ± 6.20	13.0 ± 5.33	.970
Side (Right/Left/Isthmus)	41 / 41 / 3	99 / 89 / 3	.420
Location (upper/middle/lower)	6 / 45 / 34	12 / 102 / 77	.922
Treatment parameters
Total energy delivered (KJ)	13.50 ± 5.51	13.60 ± 5.19	.659
Total ‘on-beam’ time (minutes)	47.40 ± 23.16	46.55 ± 20.25	.749
Average energy per each pulse (J)	289.57 ± 28.99	297.14 ± 34.15	.364
Efficacy/volume reduction ratio^b
At 3 months (%)	56.87 ± 18.16	48.19 ± 23.07	.128
At 6 months (%)	69.43 ± 30.07	61.84 ± 24.26	.246
≥50% shrinkage at 6 months (%)	69 (81.2)	145 (75.9)	.545

Anti-Tg: Anti-thyroglobulin autoantibody; TPO: thyroid peroxidase autoantibody; IQR = interquartile range; TSH: thyroid stimulating hormone; US: ultrasound; WHO: World Health Organization.

^a Volume of a nodule = (width × depth × length) × (π/6) where π was taken as 3.14159.

^b Volume reduction ratio = [Baseline volume – volume at visit]/[Baseline volume] × 100.Bold signifies p-value < .05.

Table 2. A comparison of thyroid function, thyroglobulin and anti-thyroglobulin auto-antibody between patients with positive (> 99 IU/mL) anti-thyroglobulin antibodies (Group I) and with negative (≤99 IU/mL) anti-thyroglobulin antibodies (Group II).

Variable	Group I (n = 85)	Group II (n = 191)	p-value
Pre-ablation
TSH (mIU/L)	1.69±2.47	1.40±2.14	.891
FT4 (pmol/L)	16.51±4.40	16.63±2.89	.482
Tg (ng/mL)	220.81±808.38	331.79±883.59	<.001
Anti-Tg (IU/mL)	547.89±865.25	≤99.0±0.0	<.001
Day 4 post-ablation
TSH (mIU/L)	1.22±1.28	0.97±1.80	.189
FT4 (pmol/L)	19.36±7.95	21.13±16.22	.625
Tg (ng/mL)	1025.11±1716.97	2041.50±1858.53	<.001
Anti-Tg (IU/mL)	460.15±822.70	≤99.0±0.00	<.001

anti-Tg: anti-thyroglobulin autoantibody; FT4 : free thyroxine level (normal: 12–21 pmol/L); Tg = thyroglobulin; TSH: thyroid stimulating hormone (normal: 0.35–4.78 mIU/L).

Table 3. Bivariate Pearson’s correlations between change in serum thyroglobulin (Tg) and anti-Tg and baseline characteristics, treatment parameters and extent of nodule shrinkage for patients with positive anti-Tg (i.e. Group I only).

Variable	Serum Tg		Serum anti-Tg		% Change from Baseline to day 4^a
	Baseline	Day 4	Baseline	Day 4	Serum Tg	Serum anti-Tg
Age at treatment (years)
Correlation coefficient	0.014	0.048	−0.110	−0.156	0.009	0.149
Significance (two-tailed)	0.906	0.748	0.317	0.264	0.953	0.308
Body mass index (kg/m^2)
Correlation coefficient	0.006	0.066	−0.104	−0.171	−0.175	0.121
Significance (two-tailed)	0.960	0.546	0.486	0.220	0.251	0.408
Nodule size (cm)
Correlation coefficient	0.405	−0.098	0.435	−0.100	0.303	0.058
Significance (two-tailed)	0.007	0.531	0.030	0.635	0.141	0.784
Nodule volume (cm^3)
Correlation coefficient	0.526	−0.213	0.528	−0.222	0.335	−0.015
Significance (two-tailed)	<0.001	0.170	0.007	0.287	0.101	0.945
Serum TSH (mIU/L)
Correlation coefficient	−0.150	0.011	−0.392	0.051	0.104	−0.066
Significance (two-tailed)	0.187	0.923	0.006	0.716	0.495	0.651
Serum-free T4 (pmol/L)
Correlation coefficient	−0.068	0.132	−0.143	0.045	−0.120	0.241
Significance (two-tailed)	0.553	0.227	0.339	0.746	0.433	0.096
Anti-TPO (IU/mL)
Correlation coefficient	−0.181	0.144	−0.286	0.046	0.086	−0.143
Significance (two-tailed)	0.111	0.189	0.052	0.746	0.573	0.326
Total energy delivered (KJ)
Correlation coefficient	0.310	−0.276	0.178	−0.267	−0.081	0.095
Significance (two-tailed)	0.009	0.015	0.243	0.059	0.606	0.524
Total treatment time (min)
Correlation coefficient	.186	−0.278	−0.024	−0.213	−0.071	0.109
Significance (2-tailed)	0.118	0.114	0.874	0.133	0.653	0.466
Mean power per voxel (J)
Correlation coefficient	0.253	−0.187	0.334	−0.215	−0.094	0.126
Significance (2-tailed)	0.036	0.108	0.029	0.139	0.558	0.410
6-month VRR
Correlation coefficient	−0.551	0.269	−0.660	0.443	−0.249	−0.602
Significance (2-tailed)	0.002	0.166	0.014	0.130	0.413	0.030

TPO: thyroid peroxidase; VRR: volume reduction ratio.

^a Change (%) = [Level on Day 4 – Baseline level]/[Baseline level] × 100.Bold signifies p-value < .05.