Urinalysis

The Visual Inspection

During the visual inspection, the biomedical scientist observes the urine's colour and how clear it is (its clarity). Urine can be a variety of colours, most often shades of yellow, from very pale or colourless to very dark or amber.

Unusual or abnormal urine colours can be the result of a disease process or of eating certain foods. For example, some people excrete red-coloured urine after eating beetroots. Under this circumstance, the reddish colour of the urine, from the natural pigment of beetroots, is no cause for worry. However, red-coloured urine can also occur when blood is present in the urine; if this is the case, seek medical attention.

Some substances that get into the urine during collection will affect urine colour. In women, blood from haemorrhoids or menstrual blood can easily get into the urine sample unintentionally (contaminating it) and cause it to look red. This is why it is important to cleanse the genitalia and to follow the directions provided by health care providers for urine collection. Once this contaminating blood is in the urine, it will be detected during the chemical phase of a urinalysis, and your doctor will assume it came from the urinary tract. The importance of blood in urine is discussed further in the chemical and microscopic examination sections.

The depth of urine colour is also a crude indicator of urine concentration:

• Pale yellow or colourless urine indicates a dilute urine where lots of water is being excreted.
• Dark yellow urine indicates the excretion of waste products in as little water as possible (for example, during a fever, or the first morning urine).

Accurate measurement of urine concentration can be done using a chemical test, called specific gravity, which measures the amount of dissolved substances in the urine water.

Urine clarity refers to how clear the urine is. Usually laboratories report the clarity of the urine using one of the following words: clear, slightly cloudy, cloudy, or turbid. “Normal” urine can be clear or cloudy. The clarity of the urine is not as important as the substance that is causing the urine to be cloudy. Substances that cause cloudiness but that are not considered unhealthy include mucous, sperm and prostatic fluid, cells from the skin, normal urine crystals, and contaminants (like body lotions and powders). Other substances that can make urine cloudy (such as red blood cells, white blood cells, or bacteria) indicate a condition that requires attention.

Urine colour and clarity can indicate what substances may be present in urine. However, confirmation of suspected substances is obtained during the chemical and microscopic examinations.