A 15-year-old boy with cystic fibrosis is brought to the emergency department for epistaxis. He first noticed intermittent nose bleeds a few days ago after a week of nasal congestion with low-grade fever. The bleeding worsened today and has been difficult to control. The patient has also had easy bruising for the past 2 months. He has not been taking his prescribed medications. Temperature is 37 C (98.6 F), blood pressure is 108/72 mm Hg, pulse is 90/min, and respirations are 18/min. The patient is alert and cooperative. There is active bleeding from the left naris. The pupils are equal and reactive. Breath sounds are coarse bilaterally, and cardiac examination is unremarkable. The abdomen is soft and nontender with no organomegaly. Strength and sensations are 5/5. Reflexes are equal bilaterally, and gait appears normal. Skin examination shows diffuse bruises along the extremities. Which of the following is the most likely cause of this patient's symptoms?

Question

A 15-year-old boy with cystic fibrosis is brought to the emergency department for epistaxis.  He first noticed intermittent nose bleeds a few days ago after a week of nasal congestion with low-grade fever.  The bleeding worsened today and has been difficult to control.  The patient has also had easy bruising for the past 2 months.  He has not been taking his prescribed medications.  Temperature is 37 C (98.6 F), blood pressure is 108/72 mm Hg, pulse is 90/min, and respirations are 18/min.  The patient is alert and cooperative.  There is active bleeding from the left naris.  The pupils are equal and reactive.  Breath sounds are coarse bilaterally, and cardiac examination is unremarkable.  The abdomen is soft and nontender with no organomegaly.  Strength and sensations are 5/5.  Reflexes are equal bilaterally, and gait appears normal.  Skin examination shows diffuse bruises along the extremities.  Which of the following is the most likely cause of this patient's symptoms?

Quizplus · Accepted Answer

11ec25c8_d699_7235_bc81_05712b20bd6d_MD0003_00 This patient with cystic fibrosis (CF) has bruising and epistaxis likely due to deficiency of vitamin K, a fat-soluble vitamin. Patients with CF are at increased risk for vitamin K deficiency because defective chloride transport causes viscous exocrine secretions to block pancreatic ducts, leading to pancreatic insufficiency. Impaired secretion of pancreatic enzymes (eg, lipase) results in the malabsorption of fats and fat-soluble vitamins (ie, A, D, E, and K). In patients with CF, nonadherence to pancreatic enzyme replacement and fat-soluble vitamin supplementation, as seen here, increases the risk of bleeding diatheses. Because vitamin K normally acts as an important cofactor in the hepatic activation of coagulation factors II, VII, IX, and X, deficiency results in low levels of activated vitamin K-dependent coagulation factors. PT is prolonged due to deficiency of activated factor VII; activated PTT is typically normal but can be prolonged with severe deficiency. hepatic activation activated factor VII Symptoms include easy bruising and mucosal bleeding (eg, epistaxis), as seen in this patient. Acute bleeding due to vitamin K deficiency is treated with vitamin K replacement. (Choice B) Increased coagulation factor consumption, as seen with disseminated intravascular coagulation, can cause mucosal bleeding but is triggered by an underlying condition such as sepsis, trauma, or malignancy, none of which are present in this patient. (Choice C) Increased platelet sequestration occurs with hypersplenism, which is common with sickle cell disease and leukemia but not CF. In addition, patients with hypersplenism have an enlarged spleen, which is not seen in this patient. (Choice D) Reduced activity of ADAMTS13, the enzyme that cleaves von Willebrand factor, describes the pathogenesis of thrombotic thrombocytopenic purpura (TTP), an acute and rapidly progressive disorder. Although TTP can cause acute bleeding, chronic bruising would not be expected. In addition, abdominal pain and neurologic symptoms (eg, confusion) are often present but are not seen here. (Choice E) Deficiency of vitamin C can cause easy bruising and bleeding, but because it is not a fat-soluble vitamin, patients with CF are not at risk for vitamin C malabsorption. Educational objective: Patients with cystic fibrosis are at risk for fat-soluble vitamin (ie, A, D, E, and K) deficiency due to fat malabsorption from pancreatic insufficiency. Vitamin K is an important cofactor in coagulation factor activation; deficiency causes easy bruising and mucosal bleeding. References: Routine use of daily oral vitamin K to treat infants with cystic fibrosis. (http://www.ncbi.nlm.nih.gov/pubmed/26410287) ESPEN-ESPGHAN-ECFS guidelines on nutrition care for infants, children, and adults with cystic fibrosis. (http://www.ncbi.nlm.nih.gov/pubmed/27068495)

A 15-Year-Old Boy with Cystic Fibrosis Is Brought to the Emergency