**Question:** The features of neonatal hyperthyroidism include all except -

A. Increased muscle tone
B. Weight loss
C. Increased alertness
D. Global developmental delay

**Core Concept:** Neonatal hyperthyroidism is a condition characterized by elevated levels of thyroid hormones in newborns, leading to various clinical manifestations. Thyroid hormones are essential for normal brain development and growth.

**Why the Correct Answer is Right:** The correct answer (D) "Global developmental delay" is not a feature of neonatal hyperthyroidism because the condition primarily affects the developing brain, leading to symptoms such as increased muscle tone, weight loss, and increased alertness. Global developmental delay refers to a generalized impairment in cognitive, motor, and social development, which is not the primary focus of neonatal hyperthyroidism.

**Why Each Wrong Option is Incorrect:**

A. Increased muscle tone: Neonatal hyperthyroidism can cause increased muscle tone due to the increased availability of thyroid hormones, which stimulate muscle contractions.

B. Weight loss: In contrast to hyperthyroidism, weight loss is a common feature of neonatal hypothyroidism (congenital hypothyroidism), as inadequate thyroid hormone production leads to reduced calorie consumption and weight loss.

C. Increased alertness: Hyperthyroidism can cause increased alertness due to the stimulation of the central nervous system by elevated thyroid hormones, which can lead to increased arousal and responsiveness in the newborn.

**Clinical Pearl:**

Neonatal hyperthyroidism is a clinical entity that requires prompt recognition and management. Early diagnosis and treatment are crucial to minimize neurological impairment and developmental delay in these infants.

**Correct Answer:** D. Global developmental delay