Preparation with Recombinant Human Thyroid-Stimulating Hormone for Thyroid Remnant Ablation with 131I Is Associated with Lowered Radiotoxicity

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TABLE 1

Exclusion Criteria

Parameter evaluated for damage	Exclusion criterion	No. of patients excluded
Salivary glands	History of salivary gland disorders	0
	Use of anticholinergic drugs	1
	Report of recurrent or persistent pain or enlargement of salivary glands	1
	Hyperamylasemia before ¹³¹I administration	3
Ovaries	History of oophorectomy, chemotherapy, or pelvic radiotherapy	0
	Increased FSH before ¹³¹I	20
Testes	History of chemotherapy, orchiepididymitis, cryptorchidism	1
	Varicocele or infertility	1
	Increased FSH before ¹³¹I	1
Hematologic	Known hematologic disease	0
	Neutrophils < 1,800/mm³	2
	Platelets < 150,000/mm³	1
	Hemoglobin < 12 g/dL	1
Oxidative	Diabetes	0
	Smoker	7

TABLE 2

Study Protocol

Parameter evaluated for damage	Test	Time of evaluation
Salivary glands	Serum amylase	Immediately before and 48 h after ¹³¹I^*
	Enlargement or pain in salivary glands	2 and 7 d after ¹³¹I
Ovaries	Serum FSH	Immediately before and 6 mo after ¹³¹I^*
Testes	Serum FSH	Immediately before and 6 mo after ¹³¹I^*
Hematologic	Blood count	Immediately before and 30, 45, and 60 d after ¹³¹I
Oxidative	Plasma 8-epi-PGF_2α	Immediately before and 4 d after ¹³¹I^*

↵* Significant increases in levels of amylase (4,5), FSH (6–9), and 8-epi-PGF_2α (10) after ¹³¹I were seen at these times.

TABLE 3

Characteristics of Groups A and B

Characteristic	Group A (rhTSH; n = 30)	Group B (hypothyroidism; n = 64)
Age (y)	45 ± 9.5	44 ± 11
Sex	Female: 20; male: 10	Female: 44; male: 20
Histologic type	Papillary: 27; follicular: 3	Papillary: 58; follicular: 6
Tumor size (cm)	2.7 ± 0.7	2.5 ± 0.6
Minimal extrathyroidal invasion	6 (20%)	14 (22%)
Tumor size ≤ 2 cm	10 (33.3%)	23 (36%)
Tumor size > 2 and ≤ 4 cm	11 (36.6%)	21 (33%)
Tumor size > 4 cm or extrathyroid invasion	9 (30%)	20 (31.2%)
Interval between thyroidectomy and ablation (d)	102 ± 21	106 ± 18
TSH immediately before ¹³¹I administration (mIU/L)^*	118 ± 28.5	85 ± 23

TABLE 4

¹³¹I-Related Adverse Effects in Groups A and B

Outcome	Group A (rhTSH)	Group B (hypothyroidism)	P
Elevated FSH 6 mo after ¹³¹I
Men	4/9 (44.4%)	16/18 (89%)	0.03
Women	1/13 (7.7%)	6/30 (20%)	0.4
Mean increase of FSH
Men	105%	236%	<0.001
Women	65%	125%	<0.001
Hyperamylasemia 48 h after ¹³¹I^*	11/30 (36.6%)	48/60 (80%)	<0.001
Symptoms of acute sialoadenitis up to 7 d after ¹³¹I^*	9/30 (30%)	35/60 (58.3%)	0.01
Thrombocytopenia (<100,000/mm³) or neutropenia (<1,500/mm³) (lowest count) up to 60 d after ¹³¹I^†	2/28 (7%)	12/56 (21.4%)	0.1
Mean decrease of neutrophils (considering lowest count)^‡	20%	45%	<0.01
Mean decrease of platelets (considering lowest count)^‡	25%	52%	<0.01
Increased 8-epi-PGF_2α 96 h after ¹³¹I	14/25 (56%)	45/45 (100%)	<0.001
Mean increase of 8-epi-PGF_2α	60%	125%	<0.001

↵* All symptomatic patients presented with concomitant hyperamylasemia. No cause other than salivary gland damage was suspected for increase in serum amylase in any patient.
↵† One patient showed platelet count of less than 75,000/mm³ and other-neutrophil count of less than 1,000/mm³. Thrombocytopenia or neutropenia was observed 30, 45, and 60 d after ¹³¹I administration in 4, 8, and 2 patients, respectively.
↵‡ Lowest platelet count was observed 30, 45, and 60 d after ablation in 20, 44, and 20 patients, respectively. Lowest neutrophil count was observed 30, 45, and 60 d after ablation in 16, 40, and 28 patients, respectively.