Multinodular Goiter

A mass in the neck of a 65-year-old woman had grown slowly and progressively during the last 5 years. The patient was otherwise asymptomatic; in particular, there was no heat or cold intolerance, irritability, weight loss, increased appetite, palpitations, lethargy, constipation, dysphagia, or dyspnea.

The right lobe of the goiter was enlarged and multinodular; no substernal extension of the goiter was found. The neck veins were not distended. The patient was clinically euthyroid. Her pulse rate was 70 beats per minute and regular; blood pressure was 135/85 mm Hg. There was no exophthalmos nor were there hand tremors.

Laboratory findings showed a free T4 level of 17.3 pmol/L and a thyrotropin (TSH) level of 2 mIU/L. Test results for antithyroglobulin antibodies and antimicrosomal antibodies were negative. A very prominent right thyroid lobe (10.3 × 4.2 × 6.9 cm) with multiple nodules and cysts was demonstrated on an ultrasonogram. The left lobe was normal in size with a slightly echogenic nodule that measured 1.1 × 1 × 1.2 cm. The isthmus was normal. Thyroid imaging using iodine 131 showed a heterogeneous pattern of uptake; areas of intense uptake as well as areas of minimal uptake were noted.

Drs Edmond K. H. Liu and Alexander K. C. Leung of Calgary, Alberta, diagnosed a multinodular goiter in this patient. It has been suggested that mild abnormalities in thyroid hormone synthesis lead to chronic low-grade TSH stimulation. This, in turn, causes episodic growth of cells in the thyroid follicles with formation of multiple nodules. The process is complicated by hemorrhagic necrosis and fibrosis and by the development of large, colloid-filled thyroid follicles.

Patients with a multinodular goiter often are asymptomatic. Assess goiter size and thyroid function periodically. Surgical treatment may be indicated if the size of the gland causes physical symptoms or tracheal compression. A multinodular goiter usually is associated with a low risk of malignancy (approximately 0.5%).¹ The sudden enlargement of part of a multinodular goiter is often the result of hemorrhage into a nodule; however, it may indicate the growth of a malignancy. A fine-needle aspiration biopsy will confirm the diagnosis.

Before using radioactive iodine to treat hyperthyroidism associated with a multinodular goiter (Plummer disease), give antithyroid drugs to ensure the patient is euthyroid. Normal thyroid function is necessary to avoid the rare occurrence of radiation thyroiditis, which may lead to an increased release of thyroid hormone and exacerbation of cardiac and other symptoms of hyperthyroidism. Surgical treatment is another alternative.

Withhold thyroxine therapy for patients with hypothyroidism until a thyrotropin-releasing hormone level is obtained. When autonomous function is present, iatrogenic hyperthyroidism can be provoked by TSH suppression with hormonal therapy.

REFERENCE:1. George LA, Lawson VG. Multinodular goiter. In: Falk SA, ed. Thyroid Disease: Endocrinology, Surgery, Nuclear Medicine, and Radiotherapy. 2nd ed. Philadelphia: Lippincott-Raven; 1997:431-446.