Columbus, OH - November 2016
Myxedema coma, a rare presentation of severe hypothyroidism that is considered a medical emergency, is most often seen in older women. With mortality rates as high as 65 percent, recognizing the condition quickly is critical.
A recent case study from physician-scientists at Nationwide Children’s Hospital shows that myxedema coma occurs in the pediatric population as well. It actually can be the initial presentation of central hypothyroidism in children.
“When a child presents with altered mental status, myxedema coma, an extreme manifestation of severe hypothyroidism, should certainly be part of the differential diagnosis,” says Rohan K. Henry, MD, a member of the Section of Endocrinology at Nationwide Children’s Hospital and senior author of the publication in Hormone Research in Paediatrics. “Physicians think first about a toxicology screen or basic metabolic panel. Thyroid function tests also need to be considered.”
As recounted in the case study, a 7-year-old boy with chromosome q1 deletion came to the Nationwide Children’s Emergency Department twice in one week with an altered mental status, somnolence and decreased interest in play. During the first visit, he improved with intravenous fluids and was discharged.
His second visit resulted in admission to the Pediatric Intensive Care Unit. He developed hypothermia, bradycardia and hypercarbia. An electrocardiogram revealed first-degree atrioventricular heart block; initial thyroid function testing showed low free thyroxine and thyroid-stimulating hormone levels; and a repeat test eight hours later showed a normal thyroid-stimulating hormone level but a continued low free thyroxine level, meaning secondary hypothyroidism was the likely diagnosis.
An MRI of the brain found atrophy of the corpus callosum, so hormonal insufficiencies weren’t surprising. The patients also had leg and scrotal edema.
The hypothyroidism was treated with L-thyroxine -- 10µg/kg/day in three divided IV doses for the first 24 hours achieved good results, followed by 32 µg once daily for five days and 62.5 µg by mouth once oral intake improved. The boy was discharged after eight days.
According to Dr. Henry, the case shows that clinicians should suspect myxedema coma with a constellation of symptoms like the ones experienced by this patient.
“Traditionally, physicians are taught not to request the performance of thyroid function tests during an acute illness, since there is the possibility that the result will show non- specific changes in thyroid hormones, a phenomenon termed euthyroid sick syndrome,” says Dr. Henry. “In this case, free thyroxine was much lower than you would expect for euthyroid sick syndrome. When the patient started responding to the treatment, our suspicion of myxedema coma was confirmed.”
Thompson MD, Henry RK. Myxedema coma secondary to central hypothyroidism: a rare but real cause of altered mental status in pediatrics. Hormone Research in Paediatrics. 2016 Sep 16. [Epub ahead of print]