**Question:** A 3-day child vomits everything he feeds, has a distended abdomen & diarrhoea. The urine is positive for benedicts test for reducing substance. The substance in urine is –

A. Glucose
B. Urea
C. Protein
D. Fatty acids

**Correct Answer:** **D. Fatty acids**

**Core Concept:** Benedict's test is a qualitative test used to detect the presence of reducing sugars in a sample. In this context, it is being used to detect the presence of reducing substances in the urine of the child.

**Why the Correct Answer is Right:** The child presents with vomiting, distended abdomen, and diarrhoea, which are indicative of malabsorption and impaired carbohydrate digestion. Fatty acids are a type of reducing substance that are produced when carbohydrates cannot be fully digested in the small intestine due to conditions like malabsorption syndromes (e.g., lactose or galactose malabsorption).

**Why Each Wrong Option is Incorrect:**

A. Glucose: This is a type of sugar that is not a reducing substance, and would not be positive in a Benedict's test. Glucose is usually present in urine when there is excessive glucose production (e.g., diabetes mellitus) or impaired renal clearance.

B. Urea: Urea is a nitrogenous waste product formed in the liver from amino acids and is typically found in urine. It is not a reducing substance and would not be positive in a Benedict's test.

C. Protein: Protein is not a reducing substance and would not be positive in a Benedict's test. Proteinuria is usually seen in nephrotic syndromes or urinary tract infections, not reducing substances in the context of malabsorption.

**Core Concept:** In malabsorption syndromes, carbohydrates cannot be fully digested in the small intestine, leading to the production of fatty acids and ketone bodies as a result of incomplete carbohydrate fermentation in the large intestine.

**Why Each Wrong Option is Incorrect:**

A. Glucose: As explained earlier, glucose is a sugar and not a reducing substance, thus not a correct answer for a malabsorption case.

B. Urea: Urea is a nitrogenous waste product formed in the liver from amino acids and is not relevant to the malabsorption process.

C. Protein: Protein is not a reducing substance and does not match the clinical presentation of malabsorption.

**Clinical Pearl:** Fatty acid malabsorption syndromes, such as lactose or galactose malabsorption, are characterized by symptoms like abdominal pain, bloating, and diarrhoea due to the absence of lactase or galactase enzymes in the small intestine.

Fatty acids are produced as a result of incomplete carbohydrate fermentation in the large intestine, which leads to the development of ketone bodies and fatty acids. The child's urine will be positive for ketones. In this case, the urine will appear dark yellow or reddish-brown due to the