Myxedema coma is a rare yet fatal thyroid disorder that can cause acute encephalopathy in older adults. However, because the differential for AMS is so extensive (especially amongst older adults) it is highly suggested that thyroid function tests be performed, even if the patient is not diagnosed with hypothyroidism. Aging can play a role in fluctuating hormone levels (i.e. TSH, T3 and T4). This article explores how medications such as amiodarone can lead to myxedema coma in older adults.

CASE STUDY:

• 71 year old gentleman with PMH of stage 5 CKD, a. fib ( on amiodarone 200 mg), T2DM, and heart failure comes to the hospital with multifocal pneumonia, AKI, and acute encephalopathy
  • Patient was bradycardic (55 bpm), hypothermic, and ANOx 2
  • Significant nonpitting periorbital and lip edema with no edema in the lower extremities
• CXR showed cardiomegaly, pulmonary congestion, and pleural effusions
• ECG showed prolonged TW
• Chest CT showed multifocal pneumonia
• Labs showed hyponatremia, elevated BUN, and elevated creatinine
• He was placed on temporary dialysis catheter, since acute uremia could cause mental status changes. Additionally, he was given Vanco, Zosyn, and Doxycycline to treat the multifocal pneumonia (which could have also caused AMS)
• After 24 hours, patient’s mental status worsened and he became ANO x 1—he was intubated at this point and thyroid panel was done
• TSH evel was 89 when it had been 3.5 the year prior. He also had low free T3 and T4 levels
• Myxedema score was 120 (60 or above is diagnostic of myxedema coma)
  • Hypothermia= 10 pionts
  • Obtunded state = 15 points
  • Anorexia/ constipation before presentation= 5 points
  • Precipitating infectious event= 10 points
  • Bradycardia= 20 points
  • Pleural effusion= 10 points
  • Prolonged QT= 10 points
  • Pulmonary edema= 15 points
  • Cardiomegaly= 15 points
  • Hyponatremia= 10 points
• He was treated with IV Levothyroxine, IV hydrocortisone and IV liothyronine and was extubated after 3 days
• Amiodarone was discontinued and he was discharged on 125 micrograms of Levothyroxine daily

DISCUSSION:

It is believed that long-term amiodarone use induced the thyroid dysfunction in the setting of acute infection, uremia, and hyponatremia

• Therefore, it is important to consider myxedema coma in encephalopathic patients who are on this medication
• Other risk factors include being female, hypothyroidism, infection, surgery, and trauma

Amiodarone-induced myxedema coma is very rare and typically occurs 3 months-2 years after initiation of amiodarone in doses greater than 200 mg/day.

• Amiodarone is actually known to cause both hypo and hyperthyroidism!
• It is hypothesized that this patient’s amiodarone use, along with old age and other comorbidities made him more likely to become symptomatic and develop myxedema coma

This case study illustrates the importance of physician awareness of myxedema come in older patients taking Amiodarone, and should encourage us to perform thyroid function tests early in admission.