Why do patients with the carcinoid syndrome develop pellagra

[Deependra]

Why do patients with the carcinoid syndrome develop pellagra (loss of appetite, generalized weakness, abdominal pain, vomiting, stomatis and bright red glossitis, and a skin rash that is pigmented and scaling in sunlight- exposed areas)?

A) Failure to elaborate serotonin
B) Vitamin B12 deficiency
C) Thiamine deficiency
D) Niacin deficiency
E) Pyridoxine deficiency

[Deependra]

The answer is: D.

Explanation:
The amino acid tryptophan is converted to the niacin derivatives nicotinic acid and nicotinamide, coenzymes required for numerous oxidative and reductive enzymes. Niacin deficiency causes pellagra, which is a complicated syndrome involving loss of appetite, weakness, irritability, abdominal pain, bright red tongue and stomatitis, and a skin rash characterized by pigmentation and scaling, particularly in areas exposed to sunlight. Pellagra can be seen in those whose diet consists primarily of corn in parts of China, Africa, and India; in chronic alcoholics; in those with congenital defects of tryptophan absorption; and in patients with carcinoid syndrome, in which there is an increased conversion of tryptophan into serotonin.