What causes cloudy urine?

From the Guidelines

Cloudy urine is most commonly caused by urinary tract infections (UTIs), which require prompt antibiotic treatment. According to a recent study published in European Urology in 2024 1, UTIs can present with various symptoms, including changes in urine color, odor, or cloudiness, regardless of urinalysis results. This study emphasizes the importance of evaluating patients with these symptoms for potential UTIs and considering antibiotic treatment if necessary.

Common Causes of Cloudy Urine

• Urinary tract infections (UTIs)
• Dehydration
• Kidney stones or crystals
• Excess protein in urine (proteinuria)
• Excess minerals like phosphate or calcium
• Semen or vaginal discharge contamination
• Certain medications or foods

Symptoms and Treatment

The presence of cloudy urine, especially when accompanied by other symptoms like dysuria, suprapubic pain, or changes in urine odor, should prompt a medical evaluation 1. Treatment for UTIs typically involves antibiotics, and the choice of antibiotic and duration of treatment depend on the severity of the infection and patient factors.

Importance of Medical Evaluation

If cloudiness persists or is accompanied by other concerning symptoms like pain, fever, or blood in urine, a thorough medical evaluation is necessary to rule out serious conditions like kidney disease 1. Increasing water intake can help resolve dehydration-related cloudiness, but persistent or severe cases require further investigation.

From the Research

Causes of Cloudy Urine

• Cloudy urine can be caused by various factors, including:
  • Precipitated phosphate crystals in alkaline urine 2
  • Pyuria, which is the presence of pus in the urine 2
  • Urinary tract infections (UTIs) 3, 4
  • Kidney stones, particularly infection stones 3
• Other possible causes of cloudy urine include:
  • Concentrated urine, which can cause a strong odor 2
  • Non-infectious causes, such as increased cellular or non-cellular constituents of peritoneal fluid 5, 6

Diagnostic Considerations

• A complete urinalysis, including physical, chemical, and microscopic examinations, can help diagnose the cause of cloudy urine 2
• Midstream clean collection is an acceptable method for collecting urine samples, but the specimen should be examined within two hours of collection 2
• Dipstick urinalysis can be convenient, but false-positive and false-negative results can occur 2

Treatment and Management

• Treatment for cloudy urine depends on the underlying cause, such as UTIs or kidney stones 3, 4
• Antibiotic therapy may be necessary for UTIs or infection stones 3, 4
• For acute uncomplicated cystitis, trimethoprim-sulfamethoxazole, nitrofurantoin, or fosfomycin are recommended as first-line therapies 4