Cloudy urine has many potential causes. Some of these causes are more serious than others, making it important to understand when you need to seek medical attention.
Normal urine comes in many colors. It typically varies from clear (like water) to a dark amber color. The exact shade of urine is a function of many different factors, including your level of hydration, what you've eaten lately and medications you are taking among other things. Changes in urine color and clarity can often be worrisome, especially when combined with other urinary symptoms, such as increased frequency and pain or burning on urination.
The most common cause of cloudy urine is completely harmless. Excess phosphate crystals have the ability to build up in your urine. These crystals will then precipitate, making your urine cloudy. This generally happens after eating a large meal. It can also happen after drinking milk, which is high in phosphate. You can test to see if your urine cloudiness is due to phosphates. Simply take a small sample of your urine and drop a bit of acetic acid (vinegar) in to it. If it is phosphates, the urine will become completely clear immediately.
Vaginal discharge is a common cause of cloudy urine in women. This can be either due to normal vaginal secretions, or due to abnormal vaginal discharges. Vaginal discharge can have literally dozens of different causes.
Pus in the urine can cause cloudiness. However, it's important to understand that pus is usually a symptom of some other problem, such as a urinary tract infection or something like gonorrhea. Kidney infections, known as pylonephritis can cause puss and cloudiness of the urine as well. Pylonephritis will almost always be associated with flank pain, pain on urinating as well as fever and general symptoms of infection.
Bladder infections, known as cystitis, can cause cloudy urine. In these cases the cloudiness is usually due to white blood cells (leukocytes) in the urine, which are a response to the infection. A quick urine dipstick test at the doctors office can establish the presence of white cells in the urine. Most cases of cystitis have other symptoms as well. These can include a feeling of urgency, frequent urination, pain or burning on urinating, abdominal pain, and even fever or chills.
Kidney stones can also be a cause of cloudy urine. In this case, you will almost invariably be more concerned about the extreme pain caused by the stone than the color of your urine. As someone who has had three kidney stones in the past, I can assure you that the color and quality of my urine was about the last thing on my mind at the time. When the stone passes, the urine should clear up pretty quickly, although the lack of pain will be the more noticeable.
Among the more concerning causes of cloudy urine is proteinuria. This is a condition where there is excess protein in the urine, causing it to become cloudy. There are many causes of proteinuria, some of which can be quite serious. Several types of kidney problems can cause proteinuria, as well as high blood pressure. All of the possible causes of excess protein in your urine must be investigated by your doctor. Of course, only your doctor will be able to determine that the cloudiness is in fact protein, so by the time you get that part worked out, your doctor will already be involved.
In women who are pregnant, proteinuria is one of a series of symptoms that leads to a diagnosis of pre-eclampsia. This can be a very serious problem most commonly encountered in the 2nd and 3rd trimester of the pregnancy. Proteinuria combined with high blood pressure is a worrisome combination in pregnancy and needs to be evaluated by your doctor immediately.
For men, a infection of the prostate (prostatitis) can be a cause of cloudy urine. When the prostate gland gets infected, it can become quite tender. Prostatitis almost always includes more general symptoms such as fever and chills, as well as the typical urinary symptoms of frequency, pain and urgency of urination. It is important to note that prostatitis is NOT associated in any way with prostate cancer.
It's worth mentioning sexually transmitted diseases again, although I touched on gonorrhea previously. Gonorrhea is a common cause of cloudy urine. This excess discharge is due to the inflammatory response from the infection, including white blood cells.
Lastly there is the issue of finding blood in the urine. Bloody in the urine can often make the urine appear cloudy and not specifically red, especially if the quantity of blood is small. It is important to note that blood in the urine is ALWAYS abnormal and needs to be looked in to by a doctor. Women who are menstruating can often confuse red urine with normal menstruation, so care must be used in those cases to determine if the blood in a urine sample actually originated in the urinary tract or not. Blood coming from the urinary tract has literally hundreds of possible causes, all of which should be seen by a doctor.
If you experience a case of cloudy urine, it's important to talk to your doctor about the possible causes. As you can see, there are many causes, some of which can be quite series, while others are more "normal". It can often be hard to differentiate the dangerous from the benign at home. Ask your doctor if you have any concerns. Also, bear in mind that your doctor is likely to want a fresh urine sample if you go in to be seen, so be sure to ask how to provide this when you are making your appointment (it's usually best provided in the office, but not in all cases).