Which of the following is NOT a cause of ketonuria?

Ketonuria refers to the presence of ketone bodies in the urine, which typically occurs when the body is in a state of ketosis. This can happen when there is a lack of carbohydrates available for the body to use as a primary energy source.

High carbohydrate intake provides the body with sufficient glucose, which is its main energy source. When enough carbohydrates are consumed, the body does not need to break down fats for energy, leading to a reduced production of ketone bodies. Consequently, the presence of ketone bodies in the urine is unlikely when carbohydrate intake is high, making it an incorrect answer choice when looking for what does not cause ketonuria.

Conversely, fasting/starvation, low-carb diets, and extreme exercise often lead the body to enter a state of ketosis. During fasting or starvation, the body depletes its glycogen stores and starts metabolizing fat for energy, generating ketones as a byproduct. A low-carb diet similarly restricts glucose availability, prompting the body to rely on fat for energy, also resulting in ketonuria. Extreme exercise can push the body into a calorie deficit that mimics these fasting conditions, potentially increasing ketone production as well.