What is the diagnosis and treatment for central hyperthyroidism (Central Hyperthyroidism)?

From the Guidelines

Central hyperthyroidism should be diagnosed by finding elevated thyroid hormones (T3 and T4) with normal or elevated TSH levels, and treatment should primarily focus on removing the underlying cause, usually through transsphenoidal surgery to remove the pituitary tumor, as this approach has the potential to improve morbidity, mortality, and quality of life outcomes.

Diagnosis

The diagnosis of central hyperthyroidism involves several key steps, including:

• Finding elevated thyroid hormones (T3 and T4) with normal or elevated TSH levels, which differs from primary hyperthyroidism where TSH is suppressed 1.
• Identifying the underlying cause, such as a TSH-secreting pituitary adenoma or pituitary resistance to thyroid hormone.

Treatment

Treatment options for central hyperthyroidism include:

• Transsphenoidal surgery to remove the pituitary tumor, which is the primary treatment approach 1.
• Medication options, such as:

• Somatostatin analogs like octreotide (starting at 50-100 mcg subcutaneously three times daily, potentially increasing to 500 mcg) or lanreotide (60-120 mg deep subcutaneous injection every 4 weeks) 1.
• Dopamine agonists such as cabergoline (0.5-1 mg twice weekly) 1.
• Anti-thyroid medications like methimazole (10-30 mg daily) to help control hyperthyroid symptoms until definitive treatment 1.

Management

Regular monitoring of thyroid function tests is essential, as is MRI imaging to assess tumor response to therapy 1. This condition requires a multidisciplinary approach involving endocrinologists and neurosurgeons for optimal management. Key considerations in the management of central hyperthyroidism include:

• The potential benefits and risks of each treatment approach, including the potential impact on morbidity, mortality, and quality of life outcomes.
• The importance of individualized treatment planning, taking into account the specific underlying cause and clinical characteristics of each patient.

From the FDA Drug Label

Methimazole inhibits the synthesis of thyroid hormones and thus is effective in the treatment of hyperthyroidism.

The diagnosis and treatment of central hyperthyroidism are not directly addressed in the provided drug label.

• The label discusses the treatment of hyperthyroidism in general, but does not specify central hyperthyroidism.
• Methimazole is mentioned as a treatment for hyperthyroidism, but its use in central hyperthyroidism is not explicitly stated 2.

From the Research

Diagnosis of Central Hyperthyroidism

• Central hyperthyroidism is a rare condition characterized by primary overproduction of TSH by the pituitary gland, leading to thyroid enlargement and hyperfunction 3.
• The diagnosis of central hyperthyroidism is based on clinical findings, biochemical tests, and imaging techniques, including measurements of serum TSH, free T4, and free T3 levels 3, 4.
• It is essential to distinguish central hyperthyroidism from primary hyperthyroidism, which has undetectable TSH values 3.

Causes of Central Hyperthyroidism

• The two known causes of central hyperthyroidism are TSH-producing pituitary tumors (TSHomas) and the syndrome of PRTH (pituitary resistance to thyroid hormone) 3.
• TSHomas are usually benign adenomas arising from the monoclonal expansion of neoplastic thyrotropes, while PRTH is a nonneoplastic disorder caused by inherited mutations in the gene for the thyroid hormone receptor beta 3.

Treatment of Central Hyperthyroidism

• TSHomas are best treated by transsphenoidal surgical removal, with radiotherapy indicated for inoperable or incompletely resected tumors 3.
• Octreotide administration is a useful adjunct for preoperatively reducing tumor size and for the medical management of surgical treatment failures 3.
• PRTH is ideally treated by chronically suppressing TSH secretion with medications such as D-thyroxine, TRIAC, octreotide, or bromocriptine 3.
• If medical therapy is ineffective or unavailable, thyroid ablation with radioiodine or surgery may be employed, with subsequent close monitoring of both thyroid hormone status and pituitary gland size 3.