The home health nurse is monitoring an 8-month-old child with hypothyroidism taking levothyroxine (Synthroid). Which symptoms does the nurse recognize as signs of overdose? (Select all that apply)

Choice A reason: Weight gain is associated with hypothyroidism due to reduced metabolic rate, not levothyroxine overdose. Overdose causes hyperthyroidism-like symptoms, increasing metabolism, leading to weight loss, not gain. In an 8-month-old, excessive levothyroxine accelerates catabolism, making weight gain an incorrect indicator of overdose, as it reflects the underlying untreated condition. Choice B reason: Vomiting is a sign of levothyroxine overdose, as excess thyroid hormone increases metabolic rate and gastrointestinal motility, irritating the digestive tract. In infants, this hypermetabolic state can cause nausea and emesis, signaling toxicity. Monitoring for vomiting is critical, as it indicates a need to adjust the dose to prevent further complications. Choice C reason: Irritability in levothyroxine overdose results from excessive thyroid hormone stimulating the central nervous system, causing restlessness and agitation in infants. This hyperthyroid state disrupts normal neurological function, leading to behavioral changes. Recognizing irritability as a toxicity sign is essential for timely dose adjustment to avoid neurological or cardiovascular complications. Choice D reason: Tachycardia is a hallmark of levothyroxine overdose, as excess thyroid hormone increases catecholamine sensitivity, elevating heart rate. In an 8-month-old, this hypermetabolic state strains the cardiovascular system, risking arrhythmias. Monitoring heart rate is critical, as tachycardia signals toxicity, necessitating immediate dose reduction to prevent cardiac complications. Choice E reason: Diaphoresis occurs in levothyroxine overdose due to increased metabolic rate and sympathetic activation, causing excessive sweating even in infants. This hyperthyroid state elevates body temperature and energy expenditure, leading to perspiration. Recognizing diaphoresis as a toxicity sign is vital for adjusting levothyroxine to prevent systemic complications like dehydration or hyperthermia.