**Question:** A strict vegetarian, Raj Gopal - 23 years old foreign student in WMC is having lethargy, easy fatigue and palpitations. He is found to have macrocytic anemia on blood CP. He is suffering from deficiency of vitamin

A. Folic acid
B. Vitamin B12
C. Iron
D. Vitamin C

**Correct Answer:** .

**Core Concept:** Macrocytic anemia refers to a type of anemia where red blood cells have abnormally large size, typically caused by deficiency of one of the B vitamins, specifically folic acid and vitamin B12. Macrocytic anemia can also be associated with iron deficiency or chronic inflammation, but in this case, we are focusing on the B vitamins.

**Why the Correct Answer is Right:** Raj Gopal is a strict vegetarian, which puts him at risk for vitamin B12 deficiency due to limited dietary sources of this vitamin. Vitamin B12 deficiency can lead to macrocytic anemia, as it is essential for the production of red blood cells and the maintenance of DNA synthesis in the bone marrow.

**Why Each Wrong Option is Incorrect:**

**A. Folic acid:** Folic acid deficiency can also cause macrocytic anemia, but it is less common in the absence of a macrocytic anemia due to vitamin B12 deficiency. Moreover, folic acid deficiency usually presents with symptoms like oral ulcers, gastrointestinal symptoms, and neurological deficits, which are not seen in Raj Gopal's case.

**B. Vitamin C:** Vitamin C deficiency does not cause macrocytic anemia, as it is not directly involved in red blood cell production or maintenance of DNA synthesis.

**C. Iron deficiency:** Iron deficiency can cause normocytic or microcytic anemia, not macrocytic anemia. Additionally, iron deficiency is more likely to present with symptoms like fatigue, pallor, and reduced exercise tolerance, which are not the primary symptoms in Raj Gopal's case.

**D. Vitamin D deficiency:** Vitamin D deficiency is unlikely to cause macrocytic anemia, as it is primarily involved in calcium homeostasis and bone health, not red blood cell production. Vitamin D deficiency usually presents with symptoms like muscle weakness, bone pain, and osteoporosis, which are not the primary symptoms in Raj Gopal's case.

**Clinical Pearl:** In cases of macrocytic anemia, considering the patient's dietary habits (being a strict vegetarian) and the absence of other symptoms associated with options A, C, and D, vitamin B12 deficiency is the most probable cause of macrocytic anemia in Raj Gopal.