In most cases, urine that smells like ammonia is not cause for concern, but likely means the person is not getting enough water, explains MedlinePlus. Most changes in urine are not caused by disease and clear up on their own.
Some of the diseases that can cause changes in urine include a bladder infection, fistula, liver failure and ketonuria, states MedlinePlus. Diabetes that is not controlled correctly or a rare metabolism disease may cause urine that is sweet smelling. Metabolic disorders and liver disease may cause musty smelling urine. It is also possible that urine is changing color or scent due to medications or the food the person is eating. For instance, asparagus gives the urine a distinct smell.
A person should contact a doctor if odor changes in the urine occur with chills, fever, back pain or burning urination, according to MedlinePlus. These symptoms could indicate a urinary tract infection, and tests for this condition include a urinalysis and urine culture. A urine culture is a test that checks for the presence of bacteria in the urine. The urine is collected at home or in a doctor's office, then sent to a lab where tests are completed. Typically, it takes 24 to 48 hours for the results of these tests to come back.