Abstract #1413762: Acute Mesenteric Ischemia: A Rare Presentation of Severe Hypothyroidism

Abstract

Hypothyroidism has been associated with several gastrointestinal symptoms (GI) including constipation, ileus, atrophic gastritis, atony and dilation in various parts of the GI tract including myxedema megacolon. A more rarely reported association is ischemic colitis. We present a case of suspected mesenteric ischemia secondary to severe hypothyroidism. 65-year-old female with a history of oropharyngeal cancer treated with radiation therapy and Superior Mesenteric Artery syndrome with stent, presented with abdominal pain, nausea and vomiting for ten days. Imaging showed severe constipation with fluid-filled thick-walled small bowel loops. She was hemodynamically stable but with an elevated lactate (4 mmol/L) that improved with intravenous fluids. Overnight, she became disoriented, dyspneic and her abdominal pain worsened. She was upgraded to the ICU with suspected bowel ischemic. Her lactate was elevated but repeat CT was unchanged. Later, thyroid function tests were obtained showing an elevated TSH of 35.5 uIU/ml, low free T3 0.8 pg/ml and undetectable free T4. She was given a dose of intravenous levothyroxine that resulted in marked improvement in her abdominal pain and mental status by the next day. She was switched to oral levothyroxine. Over the course of her hospitalization, she developed staphylococcal bacteremia and later became obtunded requiring intubation. Over the subsequent days, she developed edema, hypothermia, bradycardia, and hypotension. Imaging showed bilateral pleural effusions, a new pericardial effusion, and ascites. She was diagnosed to be in myxedema coma and restarted on IV levothyroxine with high-dose steroids. After several days with minimal improvement in her condition, her family opted for palliative extubation. Hypothyroidism can result in decreased intestinal motility due to loss of gap junctions resulting in constipation and intestinal edema and can develop years after completion of radiation therapy as seen with our patient. We suspect that our patient’s symptoms were because of mechanical compression of the vascular supply of the small intestine due to severe dilation of the bowel wall as reported previously in cases of hypothyroidism-associated ischemic colitis. Given that the major focus was on the diagnosis of acute obstructive mesenteric ischemia, there was a delay in the diagnosis of severe hypothyroidism that later progressed to myxedema coma triggered by bacteremia. This case highlights the importance of checking thyroid function in patients with evidence of bowel dilation and ileus, since a delayed diagnosis of hypothyroidism can be fatal if left untreated.