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 –
**Core Concept**
The child in the scenario is presenting with symptoms of malabsorption, dehydration, and potential metabolic derangement, which warrants investigation into the underlying cause of his gastrointestinal symptoms and the presence of a reducing substance in his urine. The condition described is suggestive of a metabolic disorder, specifically one that affects carbohydrate metabolism.
**Why the Correct Answer is Right**
The presence of a reducing substance in the urine, coupled with the child's symptoms of vomiting, distended abdomen, and diarrhea, is highly suggestive of galactosemia, a genetic disorder affecting the metabolism of galactose, a sugar found in milk and other dairy products. The body's inability to metabolize galactose leads to its accumulation in the blood, which is then excreted in the urine, where it can be detected using Benedict's test. This test is positive for reducing substances, such as galactose, which are capable of reducing copper(II) sulfate to copper(I) oxide.
**Why Each Wrong Option is Incorrect**
**Option A:** Fructosemia - While fructosemia is another genetic disorder affecting carbohydrate metabolism, it typically presents with symptoms of fructose intolerance, such as diarrhea and abdominal pain, but is not typically associated with a positive Benedict's test.
**Option B:** Lactose intolerance - Lactose intolerance is a common condition in which individuals are unable to digest lactose, a sugar found in milk, due to a deficiency of the enzyme lactase. While it can cause symptoms similar to those described, it does not typically lead to a positive Benedict's test.
**Option C:** Sucrose intolerance - Sucrose intolerance is a rare condition in which individuals are unable to digest sucrose, a disaccharide composed of glucose and fructose, due to a deficiency of the enzyme sucrase-isomaltase. While it can cause symptoms of malabsorption, it is not typically associated with a positive Benedict's test.
**Clinical Pearl / High-Yield Fact**
Remember that a positive Benedict's test in a child with gastrointestinal symptoms and a history of dairy intake should raise suspicion for galactosemia, a genetic disorder that requires prompt diagnosis and treatment to prevent long-term complications.
**Correct Answer:** C. Galactose