Freshly voided urine is clear and transparent. Cloudy urine may be caused by crystals, deposits, white cells, red cells, epithelial cells or fat globules. Further evaluation with centrifugation, microscopic examination, heating or with ether generally determines the cause of the turbidity.
Substances that cause cloudiness but that are not considered unhealthy include mucus, sperm and prostatic fluid, cells from the skin, normal urine crystals, and contaminants such as body lotions and powders.
Causes of Turbid Urine
|Amorphous Phosphates||A normal constituent in alkaline or neutral urine |
They dissolve upon addition of a dilute acid (e.g. acetic acid).
|Amorphous Urates||A normal constituent in acid urine |
They often appear as yellow crystals
May be pink crystals ("brick dust") as a result of increased uroerythrin.
They dissolve upon warming to 40°C.
|Bacteria||Often seen as seen as a uniform cloud |
They cannot be removed by ordinary filtration or centrifugation
Confirmed on microscopic examination
|Blood (red blood cells)||Usually associated with a reddish-brown, smoky appearance to the urine |
Confirmed on microscopic examination or chemical tests for haemoglobin
|Pus (white cells)||May resemble amorphous phosphates to the naked eye |
Microscopic examination confirms leucocytes.
|Mucus and Epithelial Cells||Appear as a faint cloud (nubecula) of mucus, leucocytes and epithelial cells upon cooling and standing |
The nubecula of normal urine is probably due to nucleoprotein (phosphoprotein) and not a mucin or mucoid (glycoprotein)
Nebecula usually settles to the bottom, but in urine of high specific gravity may float near the middle.
|Colloidal Particles||Cannot be cleared from urine by filtration, centrifugation or ether |
These particles are not visible on microscopic examination
|Fat Globules||Usually give a milky appearance to urine |
Confirmed on microscopic examination and can be removed by ether.
References and Links
- Unusual urine – Clinical Cases
- Urine Color
- Urine Transparency (turbidity)
- Dipstick urinalysis
- CCC – Urinalysis
- CCC – Urine electrolytes – Urinary anion gap
- Urinalysis Overview Table
- Laboratory Urinalysis
Associate Professor Curtin Medical School, Curtin University. Emergency physician MA (Oxon) MBChB (Edin) FACEM FFSEM Sir Charles Gairdner Hospital. Passion for rugby; medical history; medical education; and asynchronous learning #FOAMed evangelist. Co-founder and CTO of Life in the Fast lane | Eponyms | Books | Twitter |