Urinalysis (Urine Test): Why and How is it Done?

What is Urinalysis?

A urinalysis is used to test your urine. It helps to evaluate signs of body infections, certain diseases or other issues through a person’s urine, and detect abnormalities helping diagnosis.

The urine test examines different aspects of the urine like:

• The presence of casts (tube-shaped proteins), cells, or crystals
• Acidity (pH levels)
• The presence of bacteria or other microorganisms
• Colour
• Odour
• Appearance 
• Whether it contains blood, protein, ketones, bilirubin, or glucose

The urine appearance helps to determine whether a person had certain health conditions.

Methods of Urinalysis

A doctor will use one or more of the following methods to examine urine. 

Visual exam

A doctor will examine the urine sample based on its appearance. This helps to detect possible abnormalities. This includes noting

• The appearance whether clear or cloudy
• The colour of the urine (dark, light, red, or colourless)
• Any abnormal odour

Dipstick test

For this test, a doctor inserts a chemically treated plastic stick into the urine sample. The colour of the stick changes based on the presence of a certain substance. This helps a doctor to look for:

• Concentration or specific gravity
• Protein
• Sugars
• Changes in pH levels or acidity
• Blood
• Bilirubin, a product of red blood cell death

Microscopic exam

This examination involves examining the urine drops under the microscope. A doctor will look for the presence of

• Casts
• Crystals
• White blood cells
• Red blood cells
• Bacteria
• Yeast

Based on all these factors, the doctor can draw some conclusions and can detect possible abnormalities. Accordingly, the doctor is able to guide further tests or treatment.

Read More : Complete Blood Count Test: Why and How is it Done?

Why is the Urinalysis Done?

Urinalysis is done:

• As a part of a routine physical or medical exam
• Prior to surgery
• As a preventive screening during pregnancy – antenatal checkup

A urinalysis may also be suggested to detect certain health conditions like:

• Urinary tract infection (UTI)
• Diabetes
• Liver disease
• Kidney disease

A doctor may use urinalysis to check on the progress of treatment or condition itself if a person is diagnosed for the conditions mentioned above.  

Also, a doctor may order undergoing a urinalysis if a person experiences certain symptoms like:

• Painful urination
• Abdominal pain
• Blood in the urine
• Back pain
• Signs of urine infection like fever, chills, and other urinary complaints

Read More : Urine Glucose Test: Why and How is it Done?

Prerequisites for Urinalysis

Before the urine test, drink plenty of water to get an adequate urine sample. However, avoid drinking excessive amounts of water as it may cause inaccurate results.

A person does not have to fast or change their diet for the test. Just before the test, ensure drinking one or two glasses of fluid, preferably water. Follow your doctor’s advice for any specific prerequisites.

Also, a patient should tell his/her doctor about their medications or supplements usage, if any, before the test. A doctor may suggest avoiding a few medicines to prevent inaccurate results. The medicines that can affect the results include:

• Metronidazole
• Riboflavin
• Anthraquinone laxatives
• Vitamin C supplements
• Nitrofurantoin
• Methocarbamol

Understanding the Urinalysis Results

Understanding the process and methods can help a person to understand the results better and what they mean. Here is some common correlation between the results of different methods of urinalysis and the possible indication.

Visual Examination Results

Yellow, straw colour, or near colourless as urine colour is considered normal. Abnormal colour may indicate a possible disease condition, something a person has taken or eaten. For example:

• The dark yellow colour may indicate dehydration.
• Greenish-brown or brown colour can be a sign of hepatitis or other liver problems.
• Green colour can be seen in people due to the effect of certain medicines like sedatives taken for a long time.
• Red or pink colour may be a sign of bleeding or simply a result of having eaten beetroots. 
• The bright yellow colour is often caused due to multivitamin supplements. 

Urine clarity refers to how clear the urine is. Normally, urine is expected to be relatively clear or slightly cloudy.

Excess cloudiness in the urine is often caused by excessive substance or abnormality in the body, which may indicate the following.

• Uric acid crystals – a possible sign of gout
• White blood cells – a possible sign of infection
• Prostate fluid
• Excess protein (proteinuria)
• Fungus – including yeast (Candida)
• Pus – a sign of infection
• Bacteria – including sexually transmitted bacteria
• Semen – a sign of retrograde ejaculation
• Red blood cells – a possible sign of bleeding
• Calcium crystals – a possible sign of kidney stones

Chemical Examination Results

A chemical exam is conducted by using reagent strips impregnated with reactive chemicals and dipped into the urine. Any abnormality in the urine triggers a colour change within seconds.

A doctor often uses this test to check the following:

• Nitrites – suggestive of a bacterial infection
• Leukocytes – a sign of infection
• Urobilinogen – seen with hepatitis and liver disease
• Specific gravity – which measures urine concentration
• Glucose – elevation may suggest diabetes
• Protein – elevation may suggest kidney impairment
• Erythrocytes – a possible sign of bleeding
• pH – which measures how acidic is the urine
• Bilirubin – a yellowish pigment associated liver problems
• Ketones – elevation may suggest diabetes

Microscopic Examination Results

In this exam, a doctor will look at urine drops under a microscope to look for the presence of

• Crystals that may indicate kidney stones
• Infectious bacteria or yeasts
• Abnormalities in white or red blood cells which may be a sign of blood disorder, kidney disease, infections, or bladder cancer.

Read More : Uric Acid Test: Why and How is it Done?

When should the Urinalysis be Repeated?

The urinalysis may be repeated to confirm the test results or note for any changes after a certain period.

Your doctor may advise repeating this urine test to check improvement in the condition after treatment. If you are at greater risk of urine infections or kidney problems or have diabetes, your doctor may advise you to repeat the test every few months.

This test is also repeated at regular intervals to monitor existing medical problems or to assess the risk of complications.

The urine test may be repeated every year, as it is also a part of the routine annual preventive health checkups.

A doctor may suggest repeating urinalysis as part of a routine health checkup or regularly, for any specific reasons like monitoring underlying health conditions or infections, pregnancy checkups, etc.

Procedure for the Urinalysis

Urinalysis simply involves a patient collecting his/her urine into a specimen cup, either at home or a doctor’s clinic. Most doctors suggest collecting the urine sample first in the morning. It is because the urine is said to be more concentrated that provides easier-to-read results.

Most commonly, a doctor recommends that a patient collects a ‘clean catch’ sample – urine collected without touching the skin of the penis or tissues of the vagina.

Follow these steps to obtain a clean sample of urine:

1. With a tissue, clean the urinary opening. Men should wipe the tip of the penis. Women should clean their labia from front to back.
2. Start to urinate into the toilet. Do not collect the initial urine stream.
3. Collect the urine into the sample container in midstream.
4. Ensure the container has at least 30 to 60 ml of urine.
5. Close the container, clean the container and lid with a tissue.

You should follow your doctor’s instructions and suggestions before undergoing a urine test.