A 55-year-old man is brought to the emergency department for abdominal pain associated with watery diarrhea. His symptoms have been progressive over the last month. He says that he is depressed and often has difficulty remembering things. The patient has a 20-year history of alcohol use disorder. On examination, he appears disheveled. A pigmented scaly skin rash is present in the malar distribution of his face, neck, and back of his hands. The rash has been present for several months and worsens on exposure to sunlight. It is determined that the patient's symptoms are secondary to lack of a specific nutrient. Activity of which of the following enzymes is most likely decreased in the patient as a result of this deficiency?

Question

A 55-year-old man is brought to the emergency department for abdominal pain associated with watery diarrhea.  His symptoms have been progressive over the last month.  He says that he is depressed and often has difficulty remembering things.  The patient has a 20-year history of alcohol use disorder.  On examination, he appears disheveled.  A pigmented scaly skin rash is present in the malar distribution of his face, neck, and back of his hands.  The rash has been present for several months and worsens on exposure to sunlight.  It is determined that the patient's symptoms are secondary to lack of a specific nutrient.  Activity of which of the following enzymes is most likely decreased in the patient as a result of this deficiency?

Quizplus · Accepted Answer

Eductional Objective: Niacin is a precursor for nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), two important cofactors for many dehydrogenase and reductase enzymes.  Niacin deficiency results in pellagra (ie, diarrhea, dementia, and dermatitis).

A 55-Year-Old Man Is Brought to the Emergency Department for Abdominal