A 10-year-old boy with cystic fibrosis is brought
To the physician because his mother has noticed that it seems to take him significantly longer to stop bleeding when he has a cut. He had been prescribed pancreatic digestive enzyme supplements because his stools were bulky and large as well as malodorous. Being a child he admits that he does not take them regularly. Physical examination shows several bruises on his skin. A deficiency in which of the following nutrients is the most likely explanation for his bleeding disorder?

Question

Quizplus · Accepted Answer

Cystic fibrosis can lead to malabsorption of fat-soluble vitamins, including vitamin K, due to pancreatic insufficiency. Vitamin K is essential for blood clotting, and its deficiency can cause prolonged bleeding.  Vitamin K is a fat-soluble vitamin. In order for the fat-soluble vitamins to be absorbed from the intestines, they must be emulsified along with all the other fatty molecules in the diet. The primary mechanism for fat emulsification is the release of bile salts from the gallbladder in response to food intake. The bile salts are synthesized from cholesterol within hepatocytes and then transported to the gallbladder via the bile canaliculi. Patients with cystic fibrosis exhibit abnormal transport of chloride and sodium across an epithelium, leading to thick, viscous secretions. In addition, there is a reduced or lack of pancreatic secretions into the gut leading to difficulty absorbing nutrients with their subsequent excretion in the feces. Individuals with cystic fibrosis also have difficulties absorbing the fat-soluble vitamins such as vitamin K.

A 10-Year-Old Boy with Cystic Fibrosis Is Brought