**Question:** One year old baby exclusively breast fed has a LCM. Hepatomegaly, severe pallor, and no spleen. The most important investigation is -

A. CBC
B. Liver function tests
C. Coombs' test
D. Splenic ultrasound

**Core Concept:** Leukopenia, Hepatosplenomegaly, and severe pallor in a breastfed baby are indicative of anemia. Anemia in a breastfed baby is mostly caused by a lack of vitamin B12, folic acid, or iron deficiency.

**Why the Correct Answer is Right:** Since the baby is exclusively breastfed, the most likely cause of the anemia is iron deficiency. Iron deficiency anemia in infants is often due to suboptimal iron intake or impaired iron absorption from breastmilk.

**Why Each Wrong Option is Incorrect:**

A. CBC (complete blood count) is crucial in diagnosing anemia but does not specifically address the underlying cause.

B. Liver function tests (LFTs) are relevant to liver function, not the cause of anemia in this case.

C. Coombs' test is used to detect autoimmune hemolysis, not to diagnose the cause of anemia in this scenario.

D. Splenic ultrasound is used to evaluate the spleen, not to diagnose the cause of anemia in this case.

**Clinical Pearl:** The correct investigation to determine the cause of anemia in a breastfed baby with hepatosplenomegaly and severe pallor is **CBC** (complete blood count) along with **iron profile** (ferritin, total iron binding capacity, and serum iron levels). These tests help evaluate iron status and identify iron deficiency as the cause of the anemia in this case.

**Core Concept:** Iron deficiency anemia is a common cause of anemia in breastfed infants due to suboptimal iron intake or impaired iron absorption from breast milk.

**Why the Correct Answer is Right:** A complete blood count and iron profile are essential to investigate the cause of anemia in a breastfed baby presenting with hepatosplenomegaly and severe pallor. These tests help assess iron status and identify iron deficiency as the primary cause.

**Why Each Wrong Option is Incorrect:**

A. CBC is important for diagnosing anemia, but iron profile is crucial to determine the cause of the anemia, specifically assessing iron status.

B. Iron profile alone is sufficient to diagnose anemia, but CBC is necessary to evaluate the overall blood picture and identify the type of anemia.

C. Serum iron levels alone cannot diagnose anemia, but a combination of CBC and iron profile can help diagnose iron deficiency anemia.

D. Unexplained hepatosplenomegaly and severe pallor can be seen in other disorders, but a combination of CBC and iron profile specifically focuses on iron deficiency, contributing to the accurate diagnosis of the cause of anemia in this case.

**Clinical Pearl:** The presence of hepatosplenomegaly and severe pallor in a breastfed infant should raise