Abstract #1408158: All Myx’d Up – A Case of Myxedema in a Patient with Alzheimer’s Dementia

Abstract

Myxedema coma is a life-threatening manifestation of hypothyroidism with an approximately 30% mortality rate. We present a case of an elderly patient with Alzheimer’s dementia diagnosed with myxedema coma based on clinical presentation - decreased responsiveness, bradycardia, hypotension, and hypothermia. He improved after getting appropriate treatment. Given that hypothyroidism and Alzheimer’s dementia may coexist and be difficult to discern, it is important for physicians to screen for thyroid disease in patients with Alzheimer’s dementia. An 89-year-old male with past medical history of Alzheimer’s dementia, hypertension, atrial fibrillation, and prostate cancer in remission presented with a three-day history of increased somnolence and delayed responses. His family reported a recent decline in mentation and a fall from his wheelchair without head trauma. On exam, the patient’s vital signs were significant for a temperature of 96.2°F, heart rate of 40 bpm, and blood pressure of 96/70 mmHg. He appeared ill and was not responsive to questions. His skin was cold to the touch. Workup was remarkable for blood urea nitrogen of 50 mg/dL, creatinine of 2.9 mg/dL, thyroid-stimulating hormone (TSH) >90.00 mIU/mL, free T4 of 0.2 ng/dL, free T3< 0.6 pg/mL, and creatinine phosphokinase of 322 U/L. Thyroid indices a year prior showed TSH of 6.69 mIU/mL and free T4 of 1.0 ng/dL. Further workup was negative for hypercapnia, hyperammonemia, vitamin B12 deficiency, HIV, and syphilis screen. CT head was without any acute changes. MRI head showed chronic microangiopathy changes. Given the concerns for myxedema coma, the patient was immediately initiated on IV levothyroxine and hydrocortisone and transferred to the general ICU. Two days later, he developed hypothermia with a nadir of 30.7°C, was intubated for airway protection, and required vasopressor support. A nasogastric tube was placed for nutritional support. Although the free T4 levels normalized with treatment, he remained minimally arousable and interactive following transfer out of ICU. Over the course of a month, the patient’s TSH normalized, and he passed a modified barium swallow. The patient was eventually medically stable to discharge to a skilled nursing facility. This case highlights the importance of checking thyroid function in elderly patients presenting with altered mental status, particularly if recent thyroid indices have not been checked. Prompt recognition and treatment of myxedema coma is necessary to implement life-saving therapy in a timely fashion. Of note, hypothyroidism is associated with an increased risk of dementia. According to one study, every 6 months of elevated TSH increases the risk of dementia by 12%. Remaining in a state of hypothyroidism for long periods increases the risk of dementia. Another study suggests that patients with high levels of TSH are more likely to develop Alzheimer’s disease than those with normal TSH levels. An important take-away point is to consider hypothyroidism in the elderly, particularly with known Alzheimer’s dementia, who are hospitalized with altered mental status.