A 58-year-old man comes to the physician with a one-year history of diarrhea. The stools are watery and accompanied by abdominal cramps. He has no fever, blood from the rectum, or foul-smelling stools. He has also experienced frequent episodes of dizziness, flushing, wheezing, and a feeling of warmth. The patient has taken herbal medicines, which failed to relieve his symptoms. He is depressed about his illness and feels hopeless about diagnosis and treatment. He appears ill. Cardiac auscultation shows a 2/6 systolic murmur over the left lower sternal border that increases with inspiration. Abdominal examination shows hepatomegaly 3 cm below the right costal margin and no abdominal tenderness. Laboratory results are as follows: This patient is at risk of developing a deficiency of which of the following vitamins or minerals?

Question

A 58-year-old man comes to the physician with a one-year history of diarrhea.  The stools are watery and accompanied by abdominal cramps.  He has no fever, blood from the rectum, or foul-smelling stools.  He has also experienced frequent episodes of dizziness, flushing, wheezing, and a feeling of warmth.  The patient has taken herbal medicines, which failed to relieve his symptoms.  He is depressed about his illness and feels hopeless about diagnosis and treatment.  He appears ill.  Cardiac auscultation shows a 2/6 systolic murmur over the left lower sternal border that increases with inspiration.  Abdominal examination shows hepatomegaly 3 cm below the right costal margin and no abdominal tenderness.  Laboratory results are as follows:  This patient is at risk of developing a deficiency of which of the following vitamins or minerals?

Quizplus · Accepted Answer

11ec25c8_d3a0_2f41_bc81_636f70a5e25c_MD0003_00 The patient's clinical features - episodic flushing and wheezing, diarrhea, and valvular heart disease with tricuspid regurgitation - are consistent with carcinoid syndrome. Carcinoids are slow-growing tumors found most commonly in the distal small intestine, proximal colon, and lung. These tumors can secrete several products, including histamine, serotonin, and vasoactive intestinal peptide, that are metabolized in the liver. Gastrointestinal carcinoid tumors often metastasize to the liver. In such cases, the liver is unable to metabolize these hormones before they are released into the systemic circulation, leading to the carcinoid syndrome. Other clinical features include cutaneous telangiectasias and tricuspid regurgitation. Serotonin is synthesized in carcinoid cells from tryptophan, which is also used in the production of niacin or nicotinic acid. Advanced disease results in increased tryptophan conversion to serotonin and its metabolite 5-hydroxyindoleacetic acid. This may result in tryptophan and niacin deficiency causing pellagra (with diarrhea, dermatitis, glossitis, angular stomatitis, and dementia). (Choices A and E) Neither calcium nor vitamin C deficiency is associated with carcinoid syndrome. (Choice B) Iron deficiency is typically not seen in patients with carcinoid syndrome. In addition, this patient's serum hemoglobin and mean corpuscular volume are within normal limits, making iron deficiency even less likely. (Choice D) Vitamin A deficiency is not seen in association with carcinoid syndrome. It occurs most commonly due to dietary deficiency or in association with fat malabsorption (eg, celiac disease, small-bowel Crohn's disease, pancreatic insufficiency). Fatty diarrhea or steatorrhea typically causes pale, greasy, and malodorous stools, unlike the watery diarrhea seen in patients with carcinoid syndrome. Educational objective: Carcinoid tumors are rare neuroendocrine tumors that cause episodic flushing, secretory diarrhea, bronchospasm, and cardiac valvular abnormalities. Carcinoid cells cause increased production of serotonin from tryptophan (required for niacin synthesis), resulting in niacin deficiency (ie, pellagra, with dermatitis, diarrhea, and dementia). References: Carcinoid syndrome: diagnosis and medical management. (http://www.ncbi.nlm.nih.gov/pubmed/16444370)

A 58-Year-Old Man Comes to the Physician with a One-Year