congenital nongoitrous hypothyroidism 5

Congenital Nongoitrous Hypothyroidism

Congenital nongoitrous hypothyroidism is a condition characterized by resistance to thyroid-stimulating hormone (TSH) leading to increased levels of plasma TSH and low levels of thyroid hormone [5]. This condition is marked by the absence or severe reduction in size of the thyroid gland, which can lead to various symptoms and complications.

Key Features:

• Increased levels of plasma TSH
• Low levels of thyroid hormone
• Absence or severe reduction in size of the thyroid gland

This condition requires prompt medical attention to ensure proper diagnosis and treatment.

Common symptoms of congenital nongoitrous hypothyroidism include:

• Decreased activity and increased sleep
• Feeding difficulty
• Constipation
• Prolonged jaundice
• Myxedematous facies (puffy-looking face)
• Large, thick tongue
• Hoarse cry
• Distended abdomen

These symptoms are a result of the shortage of thyroid hormones in affected babies. [5]

Additional features:

• Excessive sleeping
• Reduced interest in nursing
• Poor muscle tone
• Low or hoarse cry
• Infrequent bowel movements
• Significant weight gain

It's essential to note that some babies with congenital hypothyroidism may show no features of the condition, although a blood test can still confirm the diagnosis. [1][3][6]

Diagnosis:

A blood test is used to diagnose primary hypothyroidism, which shows low free T4 and high TSH levels. [4]

Diagnostic Tests for Congenital Nongoitrous Hypothyroidism

Congenital nongoitrous hypothyroidism is a condition where the thyroid gland does not produce enough thyroid hormone, but there are no visible signs of goiter (enlargement of the thyroid gland). The following diagnostic tests can be used to confirm this condition:

• Thyroid Function Tests: These tests measure the levels of thyroid hormones in the blood. Specifically, they measure the levels of thyroxine (T4) and triiodothyronine (T3), as well as the level of thyroid-stimulating hormone (TSH). Elevated TSH levels with low T4 or free T4 levels can confirm congenital hypothyroidism [5].
• Thyroid Ultrasound: This imaging test uses sound waves to create images of the thyroid gland. It can help identify any abnormalities in the gland, such as nodules or cysts, which may be contributing to the hypothyroidism.
• Genetic Testing: In some cases, congenital hypothyroidism may be caused by a genetic mutation that affects the production of thyroid hormones. Genetic testing can identify these mutations and confirm the diagnosis.

It's worth noting that the diagnosis of congenital nongoitrous hypothyroidism should be confirmed by finding an elevated serum TSH level and low T4 or free T4 level, as stated in [7].

Treatment of Congenital Nongoitrous Hypothyroidism

The primary treatment for congenital nongoitrous hypothyroidism is the administration of thyroid hormone replacement therapy. The goal of this treatment is to restore normal thyroid hormone levels in the body, which is essential for proper growth and development.

• Levothyroxine (L-T4) Therapy: Levothyroxine is a synthetic form of thyroxine (T4), a hormone produced by the thyroid gland. L-T4 therapy involves administering a daily dose of levothyroxine to replace the missing thyroid hormone in the body [7][8].
• Dosage and Administration: The dosage of L-T4 depends on the severity of the hypothyroidism and the age of the child. Treatment typically begins within the first two weeks after birth, with a daily dose of 10-15 micrograms per kilogram of body weight [5].
• Monitoring and Adjustments: Regular monitoring of thyroid hormone levels is essential to ensure that the treatment is effective and to make any necessary adjustments to the dosage [7].

It's worth noting that early initiation of L-T4 therapy, ideally within the first two weeks after birth, can prevent intellectual deficits and optimize neurodevelopmental outcomes in children with congenital nongoitrous hypothyroidism [7].

Differential Diagnosis of Congenital Nongoitrous Hypothyroidism

Congenital nongoitrous hypothyroidism is a condition characterized by the underproduction of thyroid hormones in infants, without any visible abnormalities in the thyroid gland. The differential diagnosis for this condition involves identifying other possible causes of congenital hypothyroidism that do not involve goiter (enlargement of the thyroid gland).

• Central Hypothyroidism: This is a rare form of congenital hypothyroidism caused by defects in the hypothalamic-pituitary-thyroid axis, which regulates the production of thyroid hormones. Central hypothyroidism can be due to various causes, including genetic mutations, tumors, or malformations of the pituitary gland [5][10].
• Resistance to Thyroid-Stimulating Hormone (TSH): This is a rare condition where the body's cells are resistant to TSH, leading to decreased production of thyroid hormones. It can be caused by genetic mutations affecting the TSH receptor or other components of the hypothalamic-pituitary-thyroid axis [9].
• Other Rare Causes: Other rare causes of congenital nongoitrous hypothyroidism include defects in the thyroid hormone transport proteins, such as transthyretin, and genetic syndromes that affect multiple organ systems.

It's essential to note that a comprehensive diagnostic workup is necessary to rule out these differential diagnoses and confirm the diagnosis of congenital nongoitrous hypothyroidism. This may involve laboratory tests, imaging studies, and genetic evaluations.

References: [5] by P van Trotsenburg · 2021 · Cited by 379 — Introduction. [9] A non-autoimmune condition characterized by resistance to thyroid-stimulating hormone (TSH) leading to increased levels of plasma TSH and low levels of ... [10] by P van Trotsenburg · 2021 · Cited by 384 — Congenital hypothyroidism (CH) can be defined as (variable) dysfunction of the hypothalamic–pituitary–thyroid (HPT) axis present at birth, resulting in ...