A mother reports that her 4-month-old infant is lethargic, sleeps 18 hours a day, and snores. The nurse recognizes these signs are characteristic of what?

Choice A rationale: Hypothyroidism, or an underactive thyroid gland, in infants is often congenital and characterized by insufficient thyroid hormone production. Thyroid hormones are crucial for metabolic rate regulation and neurologic development. Insufficient levels lead to a slowed metabolism, causing symptoms like lethargy and excessive sleep. Snoring can be a sign of macroglossia, or an enlarged tongue, which is also associated with congenital hypothyroidism. Choice B rationale: Hyperthyroidism, or an overactive thyroid gland, is characterized by the overproduction of thyroid hormones, leading to an increased metabolic rate. This condition would manifest in an infant with symptoms that are the opposite of those described, such as irritability, sleeplessness, and an increased appetite, not lethargy or excessive sleep. These symptoms reflect a hypermetabolic state. Choice C rationale: Type 2 diabetes mellitus is a metabolic disorder characterized by insulin resistance and hyperglycemia. While it can cause lethargy and excessive sleepiness, it is extremely rare in infants and is not associated with snoring or an enlarged tongue. The primary symptoms in this age group are more likely to be related to fluid balance and glucose control. Choice D rationale: Tay-Sachs disease is a rare, fatal, neurodegenerative genetic disorder. It results from the absence of a vital enzyme, hexosaminidase A, which leads to the buildup of gangliosides in the brain. Symptoms typically appear around 6 months of age and include a startle response, loss of motor skills, and an exaggerated response to noise, not lethargy or snoring.