It is related to the volume and concentration of a variety of substances excreted by the kidneys.
Urine odor can be a symptom of a variety of conditions, including infection, inflammation, or other conditions of the urinary tract (kidneys, ureters, bladder and urethra). Urine odor can also be caused by diseases, such as diabetes and dehydration, which affect the urinary tract as well as other body systems. Normal urine is clear and has a straw-yellow color. While the odor of urine can vary somewhat, in most cases, it does not have a strong smell. With dehydration, the urine is more concentrated and may have a stronger ammonia scent than normal. Consumption of certain foods, such as asparagus (which can impart a characteristic odor to urine), and taking some medications may be causes for changes in the odor of urine. The presence of bacteria in the urine, such as with a urinary tract infection (UTI), can affect the appearance and smell of urine. When there is an infection in the urinary tract, the urine may take on a foul-smelling odor as well as appear cloudy or bloody. Normally, urine doesn't have much of a smell to it. If you're dehydrated and your urine becomes overly concentrated, it can have a stronger-than-usual scent. Vitamins and certain foods (asparagus, for example) can give urine an unusual smell. Infection can cause the urine to smell unpleasant. If you notice a strong smell to your urine, your first thought may be that something is wrong. However, if you are a normally healthy adult, the cause may be as simple as not drinking enough fluids. Treatable conditions such as urinary tract infections or diabetes mellitus may alter the smell of urine in adults as well. Causes. Urine odor is related to the volume and concentration of a variety of substances excreted by the kidneys. Normally, urine that contains a lot of water has little to no odor. If your urine becomes highly concentrated — a high level of waste products with little water — urine odor may have a strong ammonia smell. Many foods and medications, such as asparagus or certain vitamins, can affect the odor of urine.
http://www.healthgrades.com/symptoms/urine-odor http://www.medicinenet.com/urine_odor/symptoms.htm http://www.medicinenet.com/urine_odor/symptoms.htm http://www.goaskalice.columbia.edu/answered-questions/why-does-my-urine-stink http://www.livestrong.com/article/87761-causes-strong-urine-smell/ http://www.mayoclinic.org/symptoms/urine-odor/basics/causes/SYM-20050704
what causes your urine to smell