The features of neonatal hypehyroidism include all except
**Core Concept**
Neonatal hyperthyroidism is a rare condition occurring in infants born to mothers with Graves' disease or other forms of hyperthyroidism. It is caused by the transplacental passage of immunoglobulins that stimulate the fetal thyroid gland, leading to an excessive production of thyroid hormones.
**Why the Correct Answer is Right**
In neonatal hyperthyroidism, the high levels of thyroid hormones can cause a range of symptoms, including tachycardia, goiter, and irritability. The condition can also lead to cardiac complications, such as cardiomegaly and congestive heart failure. The pathophysiology involves the stimulation of the thyroid-stimulating hormone receptor (TSH-R) by the transplacentally transferred immunoglobulins, which mimic the action of thyroid-stimulating hormone (TSH).
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because goiter is actually a feature of neonatal hyperthyroidism, not a contraindication. Goiter occurs due to the stimulation of thyroid growth by the high levels of thyroid hormones.
* **Option B:** This option is incorrect because irritability is a common symptom of neonatal hyperthyroidism. Infants with this condition may exhibit excessive crying, fussiness, and restlessness.
* **Option D:** This option is incorrect because tachycardia is a characteristic feature of neonatal hyperthyroidism. The high levels of thyroid hormones can lead to an increased heart rate and cardiac output.
**Clinical Pearl / High-Yield Fact**
Neonatal hyperthyroidism is a medical emergency that requires prompt diagnosis and treatment to prevent cardiac complications. Symptoms may appear within the first few weeks of life, and it is essential to consider this condition in any infant born to a mother with Graves' disease or other forms of hyperthyroidism.
**Correct Answer:** A.