Urine typically has a straw-yellow color although this may vary at times to a pale yellow or slightly darker yellow. At times, urine may be almost clear in color especially in a person who is urinating frequently like when using a diuretic (water tablet), consuming alcohol and drinking excessive amounts of water. Read more on urine color.
Although there may be variations in the shade of yellow, urine is almost always clear and transparent or at least translucent. This means that light can pass through it clearly or is slightly diffused. Cloudy urine, however, is almost opaque and may have a murky appearance to it. Sometimes cloudy urine may have a more mustard color bordering on a yellowish-brown hue.
What does cloudy urine mean?
Cloudy urine is a sign of pus in the urine (pyuria) which is associated with an infection. Pus is composed of white blood cells, cellular debris, necrotic tissue and pathogenic microorganisms. Most urinary tract infections are bacterial in nature and upon microscopic examination (urine cytology), these bacteria will be visible. Sometimes, cloudy or murky urine may be due to the presence of urinary clasts, protein, blood cells (whole or fragments), mucus, epithelial cells or an excess of normal components of urine. Phosphates and urates may cause the urine to appear cloudy if it is left to stand for a period of time although initially the urine is clear.
Foul Smelling Odor
Cloudy urine that has a foul odor (fishy), especially if it is accompanied by a foul urethral discharge, is most likely due to a urinary tract infection. However, a lack of odor and discharge does not exclude an infection as a possible cause of cloudy urine. Sometimes vaginal discharge may mix with urine in the toilet bowl and contribute to a cloudy appearance. With men, the retrograde flow of semen (retrograde ejaculation) into the urinary bladder may also contribute to a murky appearance of the urine.
Causes of Cloudy Urine
Most urinary tract infections are ascending bacterial infections. This means that the bacteria enter through the urethra and the infection progresses up to the bladder and may also affect the prostate gland in men. Viruses, fungi, protozoa and other parasites may also be responsible. Most of these infections may be due to bacteria found in the bowel or skin, or it may be sexually transmitted infections. UTI’s usually present with frequent urination, burning pain upon urination (dysuria), urgency to urinate and pelvic discomfort or pain.
These infections are discussed further under :
- Urethritis, Gonococcal and Nongonococcal Urethritis
- Cystitis, Bladder Infection
- Prostatitis (Men)
- Pyelonephritis (kidney)
Although most cases of cloudy or murky urine are due to a urinary tract infections, a number of renal and metabolic disorders may contribute to cloudy urine. Apart from abnormal vaginal discharge due to an infection, the urine will not have a foul smelling odor, although a strong odor may be reported in some conditions.
Below is a list of other conditions that may contribute to a cloudy or murky urine, or result in similar disturbances of the urine color and consistency.
- Abnormal vaginal discharge (women)
- Proteinuria, protein in urine
- Foamy urine
- Kidney stones
- Hematuria (blood in urine), painless hematuria
- Hyperphosphatemia – kidney failure, hypoparathyroidism, diabetic ketacidosis
Article reviewed by Dr. Greg. Last updated on February 20, 2011