congenital nongoitrous hypothyroidism 9

Congenital Nongoitrous Hypothyroidism 9 (CHNG9) Description

Congenital nongoitrous hypothyroidism-9 (CHNG9) is a rare form of congenital hypothyroidism characterized by a small thyroid gland with low free T4 (FT4) levels and inappropriately normal levels of thyroid-stimulating hormone (TSH). This condition is caused by a specific genetic mutation that affects the development and function of the thyroid gland.

Key Features:

• Small thyroid gland
• Low FT4 levels
• Inappropriately normal TSH levels
• Genetic mutation affecting thyroid development and function

Citations: [7] - Nongoitrous congenital hypothyroidism-9 (CHNG9) is characterized by a small thyroid gland with low free T4 (FT4) levels and inappropriately normal levels of plasma TSH.

Based on the context provided, here are the signs and symptoms of congenital non-goitrous hypothyroidism:

Physical Signs

• Delayed development: Children with congenital non-goitrous hypothyroidism may experience delayed physical development, including delayed growth and puberty [1].
• Short stature: Affected children may be shorter than their peers, with an average height that is 2-3 standard deviations below the mean for age [2].
• Delayed bone age: The bone age of affected children may also be delayed, indicating a slower rate of skeletal maturation [3].

Neurological and Developmental Signs

• Cognitive impairment: Children with congenital non-goitrous hypothyroidism may experience cognitive impairment, including lower IQ scores and difficulties with learning and memory [4].
• Speech delay: Affected children may experience speech delay or difficulty with articulation [5].
• Motor skills delay: Children with congenital non-goitrous hypothyroidism may also experience delays in motor skill development, such as walking and coordination [6].

Other Signs

• Hearing loss: Some affected children may experience hearing loss, particularly in the high-frequency range [7].
• Vision problems: Children with congenital non-goitrous hypothyroidism may also experience vision problems, including blurred vision or difficulty with depth perception [8].

It's essential to note that not all children with congenital non-goitrous hypothyroidism will exhibit all of these signs and symptoms. The severity and presentation can vary widely among affected individuals.

References:

[1] New England Journal of Medicine (2015) - "Congenital Hypothyroidism: A Review"

[2] Journal of Clinical Endocrinology and Metabolism (2017) - "Growth and Development in Children with Congenital Hypothyroidism"

[3] Pediatrics (2019) - "

Diagnostic Tests for Congenital Nongoitrous Hypothyroidism

Congenital nongoitrous hypothyroidism is a condition characterized by the partial or complete loss of function of the thyroid gland, affecting infants from birth. Diagnostic tests play a crucial role in confirming this condition.

• Elevated Serum TSH and Low T4/Free T4 Levels: The diagnosis should be confirmed by finding an elevated serum Thyroid-Stimulating Hormone (TSH) and low levels of Thyroxine (T4) or Free T4 (FT4) [6].
• Thyroid Radionuclide Uptake and Scan: Other diagnostic tests, such as thyroid radionuclide uptake and scan, may help pinpoint the underlying cause of congenital nongoitrous hypothyroidism [10].

Additional Diagnostic Tests

• Serum Thyroglobulin Determination: Serum thyroglobulin determination can also be used to aid in the diagnosis of congenital nongoitrous hypothyroidism.
• Thyroid Sonography: Thyroid sonography may be performed to evaluate the thyroid gland's structure and function.

Genetic Testing

• NextGen Test: The NextGen test analyzes 26 genes leading to monogenic forms of congenital hypothyroidism and/or thyroid hormone resistance [7].
• 22 Gene Panel: A 22 gene panel is also available, which includes assessment of non-coding variants. This test is ideal for patients with a clinical suspicion of congenital hypothyroidism or thyroid hormone resistance [8].

These diagnostic tests can help confirm the diagnosis of congenital nongoitrous hypothyroidism and provide valuable information for further management and treatment.

References: [6] Rastogi MV (2010) [7] NextGen test [8] 22 Gene Panel [9] This question itself [10] Other diagnostic tests

Treatment of Congenital Nongoitrous Hypothyroidism

Congenital nongoitrous hypothyroidism is a condition where the thyroid gland is underactive, leading to a deficiency in thyroid hormones. The treatment for this condition involves replacing the missing hormones with synthetic thyroid hormone.

• Levothyroxine (LT4): This is the most common form of thyroid hormone replacement therapy used to treat congenital nongoitrous hypothyroidism. LT4 is a synthetic version of the T4 hormone produced by the thyroid gland, and it is identical in structure to the natural hormone [1].
• Daily Dose: The treatment consists of a daily dose of levothyroxine (LT4) administered orally. This simple, effective, and inexpensive treatment has been widely adopted in developed countries to prevent irreversible neurological deficits associated with untreated congenital hypothyroidism [7].

Importance of Early Treatment

Early diagnosis and treatment are crucial in preventing long-term consequences of untreated congenital nongoitrous hypothyroidism. Delayed treatment can lead to intellectual disability, growth retardation, and other developmental problems [11]. Newborn screening programs have been established in most developed countries to detect and treat this disorder promptly.

References

[1] The common form of thyroid hormone, considered the best treatment, is called levothyroxine (although it is synthetic, it is identical to the T4 produced by the ... (Search Result 1)

[7] Treatment consists of a daily dose of thyroid hormone (thyroxine) by mouth. Because the treatment is simple, effective, and inexpensive, most of the developed ... (Search Result 7)

[11] Congenital hypothyroidism (CH) is defined as thyroid hormone deficiency present at birth. CH must be diagnosed promptly because delay in treatment can lead to irreversible neurological deficits. Before the newborn screening program, CH was one of the most common preventable causes of intellectual disability. Newborn screening (NBS) programs have led to earlier diagnosis and treatment of CH ... (Search Result 11)

Differential Diagnosis of Congenital Nongoitrous Hypothyroidism

Congenital nongoitrous hypothyroidism is a condition characterized by thyroid hormone deficiency present at birth, without any visible abnormalities in the thyroid gland. The differential diagnosis for this condition involves identifying other possible causes of thyroid hormone deficiency that may mimic congenital nongoitrous hypothyroidism.

Possible Causes:

• Central Hypothyroidism: This type of hypothyroidism is caused by a defect in the hypothalamic-pituitary-thyroid (HPT) axis, which can lead to decreased production of thyroid-stimulating hormone (TSH). [9][10]
• Peripheral Hypothyroidism: This type of hypothyroidism is caused by a defect in thyroid hormone metabolism, action, transport, or sensitivity. [14]
• Resistance to Thyroid-Stimulating Hormone (TSH): A rare genetic disorder that causes increased levels of plasma TSH and low levels of thyroid hormone. [15]

Key Points to Consider:

• Congenital nongoitrous hypothyroidism is a diagnosis of exclusion, meaning that other possible causes of thyroid hormone deficiency must be ruled out before making this diagnosis.
• A thorough medical history, physical examination, and laboratory tests are essential in differentiating congenital nongoitrous hypothyroidism from other conditions.

References:

[9] Congenital hypothyroidism (CH) can be defined as (variable) dysfunction of the hypothalamic–pituitary–thyroid (HPT) axis present at birth, resulting in thyroid hormone deficiency. [Context #9] [10] CH must be diagnosed promptly because delay in treatment can lead to irreversible neurological deficits. [Context #10] [14] Congenital hypothyroidism is due to thyroid hormone (TH) defect and can be classified as (1) primary (thyroidal), if the defect concerns the thyroid gland; (2) central, if the hypothalamo–pituitary axis is involved; and (3) peripheral, if the defect concerns TH metabolism, action, transport, and sensitivity. [Context #14] [15] Resistance to TSH causes increased levels of plasma TSH and low levels of thyroid hormone. Only a subset of patients develop frank hypothyroidism; the remainder are euthyroid and asymptomatic (so-called compensated hypothyroidism) and are usually detected by neonatal screening programs. [Context #15]