Chapter 192: Hyperthyroidism

Patient Story

A 12-year-old girl presents with fatigue, palpitations, and inability to sleep. She has been an excellent student in school but has had increasing difficulty concentrating in class and difficulty focusing her eyes. Family history was significant for thyroid disease in her mother (hypothyroid) and maternal aunt (Graves’ disease [GD]). On examination, her pulse is 105 beats per minute, blood pressure 112/60 mm Hg, and she is mildly underweight with a BMI of 15. She has a mild resting tremor, proptosis (R >L), and her thyroid exam reveals a slightly enlarged but symmetric gland (Figure 192-1). You obtain blood work that reveals a low thyroid-stimulating hormone (TSH) and an elevated free thyroxin level (T4). A thyroid scan and uptake shows a diffusely increased intake of 54 percent with no nodules (Figure 192-2). The patient was diagnosed with GD and the therapeutic options are presented to the family.

Introduction

GD is an autoimmune thyroid disorder characterized by circulating antibodies that stimulate the thyroid-stimulating hormone (TSH) receptor and resulting in hyperthyroidism.¹

Synonyms

Thyrotoxicosis (clinical state resulting from inappropriately high thyroid hormone levels); hyperthyroidism (thyrotoxicosis caused by elevated synthesis and secretion of thyroid hormone), autoimmune hyperthyroidism, von Basedow’s disease (in Europe).

Epidemiology

• GD is the most common cause of thyrotoxicosis in children (up to 95 percent of cases), with a prevalence in children and adolescents of between 1:2000 and 1:10,000 and an incidence between 0.1 and 3 per 100,000.^2,3 The incidence peaks in adolescence; only 1 to 5 percent of cases of childhood hyperthyroidism begin before the age of 16 years.⁴

• Similar to adults, there is a female predominance of between 3:1 to 5:1.⁴

• Autoimmune hyperthyroidism can occurs in about 2 percent of infants born to mothers with GD, but is usually transient (resolving in 3 to 12 weeks).^4,5 Cases of persistent congenital hyperthyroidism and non-autoimmune familial hyperthyroidism due to mutations in the TSH-receptor gene have been reported.⁴

• Rare forms of hyperthyroidism in children include pituitary adenomas, functioning thyroid nodules, pituitary resistance to thyroid hormones, and ingestion thyroid hormone or iodine.⁴ Thyrotoxicosis of variable duration can also occur as part of Hashimoto thyroiditis (see Chapter 191, Hypothyroidism). Authors of one ...