Which condition is characterized by neurologic symptoms such as lethargy and seizures in newborns?

The condition characterized by neurologic symptoms like lethargy and seizures in newborns is hypoglycemia. In this condition, there is an abnormally low level of glucose in the blood, which is crucial for brain function. Since the brain relies heavily on glucose as its primary energy source, inadequate glucose can lead to symptoms such as irritability, lethargy, seizures, and, in severe cases, may result in neurological damage.

In newborns, certain factors can predispose them to hypoglycemia, including prematurity, low birth weight, maternal diabetes, or inadequate feeding. Early recognition and treatment of hypoglycemia are vital in preventing further neurological complications.

The other conditions listed have different clinical presentations and implications. Anemia of prematurity primarily involves low red blood cell counts and is usually associated with pallor rather than neurologic symptoms. Physiologic anemia is a natural process that occurs as fetal hemoglobin is replaced with adult hemoglobin, and it typically doesn't cause immediate neurologic symptoms. Polycythemia refers to an increased concentration of red blood cells, which may lead to other complications but does not directly present with neurologic symptoms like lethargy or seizures.