**Question:** In pellagra, all are seen except?

A. Diarrhea
B. Agitation
C. Encephalopathy
D. Haematemesis

**Core Concept:**
Pellagra is a nutritional deficiency disease primarily caused by deficiency of niacin (vitamin B3). The disease is characterized by three "Ds" - dermatitis, diarrhea, and dementia. Additionally, it can involve the gastrointestinal tract (diarrhea), central nervous system (encephalopathy), and the cardiovascular system (haematemesis).

**Why the Correct Answer is Right:**
The correct answer (D) is "Haematemesis" or vomiting of blood. Haematemesis is a manifestation of the cardiovascular system involvement in pellagra, specifically the gastrointestinal tract. Since haematemesis is a cardiovascular event, it is not part of the three "Ds" and hence is not typically seen in pellagra patients.

**Why Each Wrong Option is Incorrect:**

A. Diarrhea (Option A) - Diarrhea is a common gastrointestinal symptom in pellagra patients as it is a manifestation of the gastrointestinal tract involvement.
B. Agitation (Option B) - Agitation is a neurological symptom seen in pellagra patients due to central nervous system involvement.
C. Encephalopathy (Option C) - Encephalopathy is a neurological symptom seen in pellagra patients due to central nervous system involvement.

**Clinical Pearl:**
Pellagra is a classic example of how a single nutrient deficiency can manifest with a wide array of symptoms across different organ systems. It highlights the importance of maintaining a balanced diet and preventing micronutrient deficiencies.

**Correct Answer:** D. Haematemesis (vomiting of blood)

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**Explanation:**

Pellagra is a deficiency disease caused by insufficient intake or absorption of niacin (vitamin B3). It is primarily characterized by the presence of three "Ds" - dermatitis, dementia, and diarrhea (gastrointestinal tract involvement). Haematemesis (vomiting of blood) is a manifestation of cardiovascular involvement rather than the gastrointestinal tract, which is seen in the three "Ds". Therefore, haematemesis is not typically seen in pellagra patients.

Pellagra is caused by a deficiency of niacin, a vitamin B3, which is essential for various cellular functions, including the generation of NAD+ (Nicotinamide adenine dinucleotide), an important co-enzyme in cellular respiration and DNA repair. Adequate niacin intake is crucial for maintaining the integrity of the gastrointestinal tract, skin, and nervous system. The deficiency results in inflammation of the tongue, dermatitis, and gastrointestinal tract symptoms like diarrhea, dysphagia, and malabsorption of nutrients. Additionally, cognitive impairment (encephalopathy) and psychiatric symptoms (dementia) are also seen.

In summary, haematemesis (Option D) is not part of the classic triad of pellagra symptoms because it is a manifestation of cardiovascular involvement, while pellagra primarily presents with gastrointestinal