selective pituitary thyroid hormone resistance

Selective pituitary resistance to thyroid hormone (PRTH) is a rare genetic disorder characterized by reduced responsiveness of the pituitary gland to thyroid hormones, leading to continued production of thyroid-stimulating hormone (TSH) [5]. This results in hypersecretion of T3 and T4, establishing a new equilibrium with high serum levels of free thyroid hormones together with a nonsuppressed TSH [11][12].

The clinical presentation of PRTH can vary, but it often includes symptoms such as palpitations, anxiety, tremor, heat intolerance, insomnia, and other thyrotoxic features [11]. The presence of these symptoms, despite high serum levels of free thyroid hormones, can make differentiating PRTH from generalized resistance to thyroid hormone challenging [13].

In contrast to generalized resistance, where peripheral tissues are also resistant to thyroid hormones, PRTH is characterized by normal or elevated TSH levels and no abnormalities in the pituitary gland on MRI [10][15]. This distinction is crucial for accurate diagnosis and management of the condition.

PRTH is caused by mutations in the THRB gene, which encodes the thyroid hormone receptor beta (TRβ) protein. These mutations lead to reduced responsiveness of the pituitary gland to thyroid hormones, resulting in the characteristic clinical presentation [3][6].

References: [1] Adams et al. (1994) [2] C Yu (2018) [3] R Moghe (2022) [5] Description [10] Disease Overview [11] Selective pituitary resistance to thyroid hormone and its clinical features, THRB, ... [12] Clinical resource with information about Selective pituitary resistance to thyroid hormone and its clinical features, THRB, ... [13] symptoms are subjective; differentiating selective pituitary resistance from generalised resistance can be difficult. [15] Pituitary resistance to thyroid hormone is a rare, genetic thyroid disease, due to reduced pituitary gland responsiveness to thyroid hormone, characterized by mild to moderate hyperthyroidism in association with elevated circulating thyroid hormone levels, normal or elevated thyroid stimulating hormone, and no abnormalities of the pituitary gland on MRI.

Selective Pituitary Resistance to Thyroid Hormone (PRTH) Signs and Symptoms

Selective pituitary resistance to thyroid hormone (PRTH) is a rare condition characterized by the body's inability to respond to thyroid hormones at the pituitary gland level. This leads to an overproduction of thyroid-stimulating hormone (TSH), resulting in high levels of free thyroid hormones in the blood.

Common Signs and Symptoms:

• Thyrotoxic features: Palpitations, anxiety, tremor, heat intolerance, insomnia, weight loss, and increased stool frequency are common symptoms of PRTH.
• Goiter: A significant number of patients with PRTH (65-95%) develop goiter, which is an enlargement of the thyroid gland.
• Sinus tachycardia: An elevated heart rate can be a symptom of PRTH.
• Abnormal psychology: Some individuals may experience abnormal psychological symptoms, such as anxiety or depression.

Other Possible Symptoms:

• Short stature
• Developmental delays

Key Points to Remember:

• PRTH is characterized by an overproduction of TSH and high levels of free thyroid hormones in the blood.
• The presence of thyrotoxic features, goiter, and sinus tachycardia are common signs and symptoms of PRTH.
• Abnormal psychology and short stature can also be associated with this condition.

References:

• [1] Selective pituitary resistance to thyroid hormone (PRTH) results in continued TSH production driving hypersecretion of T3 and T4 to establish a new equilibrium, with high serum levels of free thyroid hormones together with a nonsuppressed TSH. (Source: #14)
• [2] The presence of a variety of thyrotoxic features, including palpitations, anxiety, tremor, heat intolerance, insomnia, weight loss, and increased stool frequency are common symptoms of PRTH. (Source: #4, #9, #14)
• [3] Goiter is a significant symptom of PRTH, affecting 65-95% of patients. (Source: #3)

Selective pituitary resistance to thyroid hormone (PRTH) can be challenging to diagnose, but various diagnostic tests can help confirm the condition.

Laboratory Tests

• Serum TSH levels remain nonsuppressed despite high serum levels of free T3 and T4 [9]. This is a key indicator of PRTH.
• Free T4 and Free T3 levels are typically elevated, while TSH levels remain within the normal range or slightly elevated [5].
• Genetic tests related to Thyroid Hormone Resistance, Selective Pituitary can help identify mutations in the TRβ gene, which is often associated with PRTH [2].

Imaging Studies

• Pituitary magnetic resonance imaging (MRI) may be necessary to rule out other conditions, such as a TSH-secreting pituitary adenoma [12].

Molecular Genetics Tests

• Sequence analysis of the entire coding region can help confirm the diagnosis by demonstrating mutations in the TRβ gene [3].
• Next-Generation sequencing with additional Sanger sequencing may be performed to provide full coverage of all coding exons of the TRβ gene [7].

Other Diagnostic Approaches

• Dynamic tests, such as TSH after T3 suppression and TRH stimulation tests, can help confirm the diagnosis by measuring TSH levels in response to thyroid hormone suppression and stimulation [8].
• Thyroid tissue exclusion is also an important diagnostic approach to rule out other conditions that may cause elevated TSH levels [5].

It's essential to note that a combination of these diagnostic tests may be necessary to confirm the diagnosis of selective pituitary resistance to thyroid hormone.

Treatment Options for Selective Pituitary Thyroid Hormone Resistance

Selective pituitary thyroid hormone resistance (SPRTH) is a rare condition where the pituitary gland does not respond to thyroid hormones, leading to an overproduction of thyroid-stimulating hormone (TSH). While there are no specific treatments that can cure SPRTH, various medications and therapies have been explored to manage this condition.

Medications Used in Treatment

Several medications have been used to treat SPRTH, including:

• Bromocriptine: This medication has been shown to be effective in reducing TSH levels in patients with SPRTH. It works by inhibiting the release of TSH from the pituitary gland.
• Triac (3,5,3'-Triiodothyroacetic Acid): Triac is a synthetic thyroid hormone that has been used to treat patients with SPRTH. It helps to suppress TSH production and reduce symptoms associated with this condition.

Other Therapeutic Options

In addition to medications, other therapeutic options have been explored for the treatment of SPRTH, including:

• Surgical removal of the pituitary tumor: In some cases, surgical removal of the pituitary tumor may be necessary to treat SPRTH.
• Pharmacological reduction of TSH secretion: Other medications, such as somatostatin analogs, have been used to reduce TSH production in patients with SPRTH.

References

• [3] Ohzeki et al. (1993) suggest that bromocriptine should be considered as one of the drugs for the treatment of thyroid hormone resistance.
• [9] Ohzeki et al. (1993) also recommend bromocriptine as a potential treatment option for SPRTH.
• [13] Triac has been used successfully to treat patients with thyroid hormone resistance, including those with SPRTH.

Note: The above information is based on the search results provided and may not be comprehensive or up-to-date. It's essential to consult with a healthcare professional for accurate and personalized advice on treating selective pituitary thyroid hormone resistance.

Selective pituitary thyroid hormone resistance (PRTH) is a condition characterized by resistance in the pituitary gland but not in peripheral tissues, leading to elevated serum thyroid hormone levels and normal or elevated TSH levels. When considering differential diagnosis for PRTH, several conditions need to be ruled out.

• Generalized Thyroid Hormone Resistance (GRTH): This condition is similar to PRTH but affects both the pituitary gland and peripheral tissues. GRTH can present with elevated serum thyroid hormone levels and suppressed TSH levels.
• TSH-producing Pituitary Adenoma: A rare tumor of the pituitary gland that produces excess TSH, leading to elevated serum thyroid hormone levels and normal or elevated TSH levels.
• Familial Dysalbuminemic Hyperthyroxinemia (FDH): A genetic disorder characterized by a mutation in the albumin gene, leading to elevated serum thyroid hormone levels due to impaired binding of thyroid hormones to albumin.

To differentiate PRTH from these conditions, several parameters need to be assessed:

• Clinical observation: Patients with PRTH may present with symptoms of hyperthyroidism, such as palpitations, tremor, and weight loss.
• Skull imaging: Imaging studies can help rule out TSH-producing pituitary adenoma or other structural abnormalities in the pituitary gland.
• Measurement of peripheral thyroid hormone parameters: Assessing serum free thyroxine (FT4) and triiodothyronine (FT3) levels, as well as thyroid hormone receptor binding assays, can help differentiate PRTH from GRTH.

It is essential to note that the differential diagnosis of PRTH can be challenging, and a comprehensive evaluation by an endocrinologist or other qualified healthcare professional is necessary to accurately diagnose this condition. [1][2][3][4]

References: [1] Selective pituitary resistance to thyroid hormone (PRTH) is characterized by resistance in the pituitary gland but not in peripheral tissues. Patients have elevated serum thyroid hormone levels and normal or elevated TSH levels and are clinically thyrotoxic. [Source: Context] [2] Generalized Thyroid Hormone Resistance (GRTH) can present with elevated serum thyroid hormone levels and suppressed TSH levels. [Source: Context] [3] A rare tumor of the pituitary gland that produces excess TSH, leading to elevated serum thyroid hormone levels and normal or elevated TSH levels. [Source: Context] [4] A genetic disorder characterized by a mutation in the albumin gene, leading to elevated serum thyroid hormone levels due to impaired binding of thyroid hormones to albumin. [Source: Context]