Urine consists primarily of water, waste products and electrolytes filtered from the blood by the kidneys. It is typically clear and pale yellow with a slight odor. Urine composition, color and odor normally varies, often based on your diet and hydration status. Some medicines and supplements can also affect your urine. If you are otherwise healthy and well, most urine changes represent normal variation. However, certain urine changes might signal a potentially dangerous medical condition.
Dark or discolored urine sometimes signals a significant medical problem. Pink, red or brownish discoloration might indicate blood in the urine, or hematuria. Possible causes include a urinary tract infection or stone, kidney disease or injury, and bladder or kidney cancer, among others. Dark yellow, bright yellow or orange-tinged urine could signal dehydration, decreased kidney function, liver or pancreatic disease, or breakdown of muscle tissue. Keep in mind, however, that temporary urine discoloration usually does not signal an underlying medical condition if you feel well. Medications, supplements or intensely-colored foods, such as beets, blackberries or rhubarb, might be to blame.
Strong or Unusual Odor
Urine that has a strong ammonia smell or foul odor can be a danger sign of a bladder or kidney infection. The ammonia odor occurs when infectious bacteria break down a normal urine chemical called urea, yielding aromatic ammonia. A fruity or sweet urine odor might indicate a high concentration of ketones, breakdown products of fat metabolism. This could signal the presence of undiagnosed diabetes, or loss of blood sugar control in someone living with diabetes.
As with urine color, urine odor often changes due to diet, medications or supplements. For example, eating asparagus or garlic can lead to a sulfur-like urine odor. Additionally, some people who take B vitamin supplements report a medicine-like urine odor.
Decreased or Increased Urine Volume
Persistently decreased urine production most commonly indicates significant dehydration or reduced kidney function, which can occur with a wide variety of medical conditions. High blood pressure and diabetes account for most cases of chronic kidney failure. Causes of sudden kidney failure include severe blood loss, certain bloodstream infections, and toxin or medication side effects, among others.
In the absence of high fluid intake or use of water pills, increased urine production often signals an underlying medical problem. For example, undiagnosed or poorly controlled diabetes commonly causes increased urine volume due to spillage of blood sugar into the urine. Early kidney disease might also cause a period of increased urine production due to loss of concentrating ability before urine production drops. Another disease called diabetes insipidus -- which is not the same as the blood sugar disorder diabetes mellitus -- is a less common culprit.
Hidden Danger Signs
Additional urine danger signs often cause no change in the appearance, color or odor of the urine, but can be detected with laboratory testing. For example, a dipstick urinalysis test detects increased glucose and protein, serious abnormalities that usually cause no obvious physical changes in the urine. Similarly, a small amount of blood in the urine often does not cause noticeable discoloration but can be detected with a urine dipstick test. Likewise, microscopic examination of the urine can show the presence of white blood cells, bacteria and crystals, which often signal an infection or urinary tract stone. Doctors also various urine tests to determine whether the kidneys are functioning normally.
Warnings and Precautions
See your doctor as soon as possible if you notice any urine danger signs, especially if you experience accompanying symptoms, including:
-- chills or fever
-- painful urination
-- flank or abdominal pain
-- nausea or vomiting
-- swelling of your hands, feet or face
-- dizziness, lightheadedness or fainting
-- tiredness or weakness
-- extreme thirst
-- mental changes, such as confusion or anxiety
Reviewed and revised by: Tina M. St. John, M.D.