Hypothyroidism in infancy is characterized by all EXCEPT
**Core Concept**
Hypothyroidism in infancy is a condition where the thyroid gland does not produce sufficient thyroid hormones, leading to growth and developmental delays. The primary thyroid hormone, thyroxine (T4), plays a crucial role in the regulation of metabolism, growth, and development in infants.
**Why the Correct Answer is Right**
The correct answer is related to the clinical presentation of hypothyroidism in infancy. Infants with untreated congenital hypothyroidism may present with symptoms such as constipation, dry skin, and a large tongue (macroglossia). However, they may not exhibit the typical signs of hypothyroidism seen in adults, such as weight gain or cold intolerance.
**Why Each Wrong Option is Incorrect**
**Option A:** Macroglossia is a characteristic feature of untreated congenital hypothyroidism in infancy. It is caused by the accumulation of mucopolysaccharides in the tongue due to the lack of thyroid hormones.
**Option B:** Growth delay is a common feature of untreated congenital hypothyroidism in infancy. Infants with untreated hypothyroidism may experience growth retardation, which can be reversed with early treatment.
**Option C:** Dry skin is a characteristic feature of untreated congenital hypothyroidism in infancy. The lack of thyroid hormones leads to changes in skin texture and moisture levels.
**Clinical Pearl / High-Yield Fact**
Infants with untreated congenital hypothyroidism may have a normal or even increased birth weight, but they may experience growth delay and developmental delays if left untreated.
**Correct Answer:** D.