Final answer:
Ketonuria is not common in patients who are on a low carbohydrate diet because they are typically in a state of ketosis where ketone bodies are utilized as a fuel source.
Step-by-step explanation:
Ketonuria is the presence of ketone bodies in the urine. Ketone bodies are byproducts of fat metabolism and their presence in the urine suggests that the body is using fat as an energy source instead of glucose. While ketonuria can occur in various conditions such as fasting, starvation, alcoholism, and uncontrolled diabetes, it is not common in patients who are on a low carbohydrate diet, as they are typically in a state of ketosis where ketone bodies are utilized as a fuel source.