The majority of Danish nontoxic goitre patients are ineligible for Levothyroxine suppressive therapy.

Objective: Levothyroxine suppressive therapy (LT4-therapy), aimed at shrinking thyroid nodules is controversial. Despite evidence of limited effect and long-term side-effects, questionnaire surveys indicate widespread use. Our aim was to determine, in consecutive nontoxic goitre patients, the proportion ineligible for LT4-therapy. Exclusion criteria were set up in agreement with recent guidelines.
Setting: Secondary/tertiary referral centre at University Clinic.
Subjects and Methods: During 1997-2001, 822 patients were referred to our endocrine unit on suspicion of nontoxic goitre. Patients were evaluated clinically including fine needle aspiration biopsy, thyroid scintigraphy and ultrasound. Seven-hundred and forty-five patients (627 women and 118 men; median age 47 years, range 11-90) were potential candidates for LT4-therapy. Based on guidelines we defined conditions where LT4-therapy is contraindicated. Exclusion criteria included (1) Serum TSH < 1.0 mIU/l, (2) Post-menopausal status, or males older than 60 years, (3) Thyroid volume above 100 ml, (4) Intrathoracic goitre, (5) Clinical suspicion of malignancy, (6) Dominant thyroid cyst, (7) Nondiagnostic FNA, (8) Previous ineffective LT4-therapy, (9) Elevated serum calcitonin, (10) Osteoporosis or cardiovascular disease.
Results: Of patients 84% were ineligible for LT4-therapy. In diffuse goitre (n = 35) 63%, in uninodular goitre (n = 320) 77% and in multinodular goitre (n = 390) 91% were ineligible. Main ineligibility reasons were a low serum TSH, post-menopausal status, a large goitre or clinical suspicion of malignancy.
Conclusion: The vast majority of consecutive Danish nontoxic goitre patients (84%) were ineligible for LT4-therapy. Due to low efficacy and potential long-term adverse effects on the skeleton and cardiovascular system we strongly advocate against LT4-therapy for nontoxic goitre.