Visual features
Urine color
The color of the urine sample is assessed subjectively and reported as red, brown, yellow, etc, or combination thereof, along with a modifier for the depth of color, eg, light yellow, dark red/brown, etc. Some examples of various urine colors and corresponding common causes are shown below (this is not an exhaustive list – there are many other substances, including drugs, which can influence urine color).
| Color | Possible causes |
| light to medium yellow | normal |
| colorless | very dilute urine |
| very dark yellow | very concentrated; bilirubinuria |
| red to brownish-red | hematuria; hemoglobuinuria; myoglobinuria |
| reddish-brown to brown | myoglobinuria, hemoglobinuria, methemoglobin |
| greenish tint | bilirubinuria |
Urine turbidity
The turbidity of the urine sample is gauged subjectively and reported using the descriptors: clear, slightly cloudy, cloudy, opaque, or flocculent.
Normally, fresh urine is clear to very slightly cloudy. Excess turbidity results from the presence of suspended particles in the urine. The cause can usually be determined based on the results of a microscopic urine sediment examination.
A sample of turbid urine
Common causes of abnormal turbidity
- increased cells (RBC, WBC)
- numerous crystals
- bacteria
- lipiduria (lipids often rise to the surface)
- mucus (especially in horses)
- semen
- fecal contamination
