Question

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : Acetone is volatile and imparts a characteristic odor to the breath, which is useful in diagnosis of diabetes.
Reason (R) : Individuals with untreated diabetes produces large quantities of acetoacetate, their blood contains significant amount of acetone.
In the light of the above statements, choose the most appropriate answer from the options given below :

• A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
• B. Both (A) and (R) are correct but (R) is not the correct explanation of (A)
• C. (A) is correct but (R) is not correct
• D. (A) is not correct but (R) is correct

Hint:

Remember the three main metabolic ketone bodies are Acetoacetate, $\beta$-hydroxybutyrate, and Acetone. Among these, only Acetone is exhaled through the respiratory system because of its high volatility, generating the classic "fruity breath" hallmark of DKA.

Answer 1

The Correct Option is A

Step 1: Concept:
This question tests clinical knowledge of Diabetic Ketoacidosis (DKA), a severe metabolic complication commonly seen in untreated Type 1 diabetes, focusing on its biochemical pathways and associated diagnostic clinical symptoms.

Step 2: Step-by-step Explanation:

• Analyzing Assertion (A): Patients presenting with severe, uncontrolled diabetes often exhibit a distinct "fruity" or "sweet" odor on their breath. Clinically, this is widely recognized as the smell of acetone, a highly volatile organic compound. Detecting this odor is a rapid, classic bedside diagnostic clue for ketoacidosis. Thus, Assertion (A) is factually correct.

• Analyzing Reason (R): In untreated diabetes (particularly due to absolute insulin deficiency), the body's cells cannot utilize blood glucose for energy. To survive, the body shifts to massively breaking down fat (lipolysis), releasing free fatty acids into the blood.

• These fatty acids travel to the liver, where excessive beta-oxidation overloads the metabolic pathways, leading to ketogenesis—the heavy production of ketone bodies. The primary ketone body produced is acetoacetate.

• Acetoacetate is inherently chemically unstable. In the blood, it undergoes spontaneous, non-enzymatic decarboxylation to form acetone. Because acetone is highly volatile (turns to gas easily), it diffuses from the pulmonary capillaries into the alveoli of the lungs and is physically exhaled.

• Therefore, Reason (R) perfectly details the biochemical mechanism that results in the clinical symptom described in Assertion (A).

Step 3: Final Answer:
Both statements are correct, and (R) is the correct explanation for (A).