Introduction: Newborns with congenital hypothyroidism are generally asymptomatic until 6 weeks of age. We describe a critical infant with myxedema coma presenting at 2 weeks of age. To our knowledge, this is the earliest reported critical presentation of hypothyroidism in infancy. Description: A 15-day old preterm female infant (36 weeks and small for gestational age) presented with 5 days of worsening lethargy and poor feeding described as gagging, coughing, choking and vomiting. Concerning clinical findings included hypothermia, hypotension, bradycardia, lethargy and hypotonia. Blood tests revealed a low platelet count and elevated thyroid stimulating hormone level (65uIU/mL). Newborn metabolic screen results were not immediately available. In addition to treatment for presumed sepsis (passive rewarming, fluids, antibiotics), levothyroxine and hydrocortisone were given for suspected congenital hypothyroidism and adrenal crisis. Hypotension stabilized within 6 hours. Platelet levels and neurologic findings improved after one week. Nutritional support was provided until the baby fed independently and gained weight. Workup excluded sepsis, adrenal insufficiency, epilepsy, metabolic and heart disease. After four weeks, the baby was discharged home on levothyroxine. At 5 months of age, she is thriving well and meeting developmental milestones on oral levothyroxine, with normal thyroid imaging. Discussion: Congenital hypothyroidism typically manifests after 6 weeks of age as hypotonia, lethargy, feeding difficulty, poor cry, prolonged jaundice, large fontanels, constipation, and hypothermia. Myxedema coma is a rare life-threatening emergency leading to multiorgan dysfunction due to primary or secondary hypothyroidism. Causes include autoimmunity, central hypothyroidism, congenital abnormalities and thyroid damage. Treatment includes glucocorticoids, thyroid hormone, passive rewarming, fluids, nutritional and cardiorespiratory support. Thrombocytopenia has been associated with myxedema coma and resolves with improved thyroid function, although pathophysiology is unclear. Prognosis improves with early treatment. A high index of suspicion for congenital hypothyroidism presenting as an endocrine emergency (myxedema coma) as early as 2 weeks of age may expedite treatment and improve outcomes.
Grewal et al. (Sun,) studied this question.