Normal, freshly voided urine has a faint odor owing to the presence of volatile acids. It is not generally offensive. Although not part of the routine UA, abnormal odors should be noted.

Fresh urine from most healthy persons has a characteristic odor.

Smell the urine and record perceptions.

1. The urine of patients with DM may have a fruity (acetone) odor because of ketosis.

2. UTIs result in foul-smelling urine because of the presence of bacteria, which split urea to form ammonia.

3. The urine of infants with an inherited disorder of amino acid metabolism known as maple syrup urine disease smells like maple syrup or burnt sugar.

4. Cystinuria and homocystinuria result in a sulfurous odor.

5. Oasthouse urine (Smith-Strang) disease, methionine malabsorption syndrome, causes an odor associated with the smell of a brewery (yeasts, hops).

6. With PKU, a musty, mousy smell may be evident.

7. Tyrosinemia is characterized by a cabbage-like or fishy urine odor.

8. Butyric/hexanoic acidemia produces a urine odor resembling that of sweaty feet.

1. Some foods, such as asparagus, produce characteristic urine odors.

2. Bacterial activity produces ammonia from the decomposition of urea, with its characteristic pungent odor.