When he was 18 months old, I noticed an acetone smell in my son’s breath. He had a fever so I called the doctor, who said that the smell was probably related to a virus he had, that I should wait 24 hours and see if it were still there. After 24 hours, the fever was gone and so was the smell. Now two years old, my son has had the same smell on three different mornings. It lasted a few hours, then went away. Since he now has had a cold for three days, I have noticed the smell again. My son is not drinking more and is eating less. Is this something about which I should be worried? I am taking him to the doctor tomorrow.

Acetone on the breath means that the body is likely burning its own fat. This usually occurs when there are fewer calories being consumed than is needed. So, during illnesses, including the common viruses, when food intake is less than optimal, the body switches to use its own fats. This is all perfectly normal body energy balancing itself out. If you have a good sense of smell, then it is likely there will be some ketones you can smell. It does not have any other importance except if it is related to a condition called diabetic ketoacidosis. Here, the body of a child/person with diabetes is dependent upon insulin and food to be in balance. When there is something blocking insulin or if sufficient insulin is not provided during an illness, the body does the same thing and switches to “burning” its own fat – thus ketones are created and the acetone breath occurs. DKA or diabetic ketoacidosis occurs when this becomes an extreme dangerous situation. People with diabetes are taught to check for either urine or blood ketones to monitor this situation and use this information to provide decisions about extra insulin need. If unrecognized and not properly treated, DKA can lead to coma and death so it is a potentially severe situation. There are some other very rare conditions in which ketones are elevated and would also show up either in urine, blood or on breath as well.

SB