A 72-year-old man comes to the hospital due to several episodes of bright red blood per rectum. He also has dizziness and severe fatigue. The patient has never had prior episodes of gastrointestinal bleeding. He takes lisinopril and amlodipine for hypertension. The patient is a lifetime nonsmoker. Laboratory evaluation reveals decreased levels of von Willebrand factor multimers but a normal platelet count. Upper endoscopy and colonoscopy do not identify a source of bleeding. Which of the following is most likely associated with this patient's condition?

Question

A 72-year-old man comes to the hospital due to several episodes of bright red blood per rectum.  He also has dizziness and severe fatigue.  The patient has never had prior episodes of gastrointestinal bleeding.  He takes lisinopril and amlodipine for hypertension.  The patient is a lifetime nonsmoker.  Laboratory evaluation reveals decreased levels of von Willebrand factor multimers but a normal platelet count.  Upper endoscopy and colonoscopy do not identify a source of bleeding.  Which of the following is most likely associated with this patient's condition?

Quizplus · Accepted Answer

This patient's brisk gastrointestinal (GI) bleeding with no identifiable source on upper or lower endoscopy suggests bleeding in the distal duodenum, jejunum, or ileum, which are not well visualized with standard endoscopy. Small bowel bleeding is often due to vascular malformations in the bowel wall, particularly angiodysplasias. Angiodysplasias are tortuous, dilated, thin-walled vessels lined by a layer of endothelium with or without a small amount of smooth muscle. They are thought to form due to recurrent, intermittent obstruction of distal venules in the muscularis propria, which leads to proximal arterial damage. Symptomatic angiodysplasias are most common in the GI tract and primarily occur in individuals age >60. Risk of bleeding from angiodysplasias is increased with end-stage renal disease and aortic stenosis (AS). AS is thought to trigger bleeding from angiodysplasias due to destruction of circulating von Willebrand factor (VWF) multimers when they pass through the damaged valve. Because VWF multimers play a crucial role in primary hemostasis by binding platelets to sites of endothelial injury, reduction in circulating levels of VWF increases the risk of bleeding significantly. (Choice B) Chronic liver disease is associated with portal hypertension, which can cause bleeding from gastric or esophageal varices. However, varices are generally seen on upper endoscopy. In addition, chronic liver disease is often associated with elevated INR due to deficiency in coagulation factors; VWF is not typically affected because it is primarily produced by the endothelium. (Choice C) Glucose intolerance is associated with the development of type 2 diabetes mellitus, which is characterized by excessive elevations in blood glucose following meals due to insulin resistance and impaired insulin secretion. (Choice D) Uncontrolled, resistant hypertension may be seen in patients with obstructive sleep apnea, renal artery stenosis, and primary aldosteronism. Uncontrolled hypertension is not a common cause of low VWF multimers and GI bleeding. Severe hypertension can cause anemia due to mechanical destruction of erythrocytes (eg, schistocytes). (Choice E) Vitamin B₁₂ deficiency is often caused by disorders of the GI tract, such as atrophic gastritis, celiac disease, and bacterial overgrowth in the small bowel. Although vitamin B₁₂ deficiency commonly causes megaloblastic anemia and is sometimes associated with mild thrombocytopenia, it is not tightly linked to low VWF multimers or GI bleeding. Educational objective: Angiodysplasias in the gastrointestinal (GI) tract are a common source of GI bleeding. Bleeding from angiodysplasias may be triggered by underlying aortic stenosis, which is associated with low levels of von Willebrand factor multimers; this glycoprotein is often destroyed when it passes through the damaged valve at high velocity.

A 72-Year-Old Man Comes to the Hospital Due to Several