Urinalysis (Urine testing) – Types, Process, Results Interpretation, Reference charts

A urinalysis or urine test is a non-invasive procedure to check for the composition of urine, which is helpful in detecting some types of medical conditions like diabetes, urinary tract infection, and kidney-related diseases, to name a few.

In a routine urinalysis, the urine is checked for its appearance, concentration, and composition. Any abnormalities can be linked to a particular disease or illness.

Urinalysis

Image 1: Urinalysis is a part of the routine check-up.

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Who orders a urine test?

Doctors order a routine urinalysis because it is convenient, easy, and affordable procedure. It also has a quick turnaround time. Doctors who typically orders urinalysis include:

  • Emergency room doctors
  • Gynecologist
  • Obstetricians
  • Family practitioners
  • Nephrologists
  • Rheumatologists
  • Urologists (1, 2)

 

Why is urinalysis performed?

  1. It is a part of a routine medical examinations, especially in people who are:
    1. Pregnant
    2. Pre-surgery preparation
    3. Hospital admission
  2. It helps diagnose a particular medical conditions such as:
    1. Urinary tract infection
    2. Diabetes mellitus
    3. Kidney-related diseases
    4. Liver-related diseases (2, 3)
  3. It helps in monitoring the patient’s medical condition, especially those undergoing treatments for the conditions mentioned above. It helps assess whether the treatment the patient currently receives is effective.

Different components of the body

Image 2: Different components of the body can be determined using urine as a specimen.

Picture Source: ucsfhealth.org

 

What is being checked in urinalysis?

Urinalysis consists of three things: physical, chemical, and microscopic. There are a variety of items being checked in urinalysis such as:

  • Presence of cells
  • Cellular fragments
  • Byproducts of both normal and abnormal metabolisms
  • Bacteria

The kidneys are the organs that produce urine. What the kidneys do is they filter wastes out of the blood, regulate water in the body, and conserve essential compounds in the body including proteins and electrolytes.

Anything the body does not need travels from the kidneys through ureters, bladder, urethra, and out of the body. (1, 2, and 3)

Looking at the physical composition of urine, you can easily observe the usual color and consistency – relatively clear and yellow. However, the person’s urine is not always perfect.

There might be components that are not supposed to be there such as protein, glucose, blood cells both white and red, crystals, and bacteria. Abnormalities in urine can be linked to the following:

  • Kidney-related diseases/concerns
  • Abnormal levels of a particular substance in the blood
  • Urinary tract infection

Checking the composition of urine

Visual examination/physical examination

It checks the color and clarity of urine.

 

Chemical examination

It checks for chemical substances that might be present in urine, which aids in checking the person’s health condition, urine concentration, and the existence of a particular disease.

 

Microscopic examination 

It counts the components of urine in detail such as the type of cells present, crystal formation, cast, bacteria, mucus, and other components. (4, 5)

 

Preparing for urinalysis

If it is for a routine urinalysis, the patient is allowed to eat and drink the usual way. However, if you are going to perform other tests along with urinalysis, then you might be required to undergo fasting for a particular period of time.

Aside from restricting foods, there might be some supplements and non-prescription drugs you need to completely avoid before the test. Hence, before undergoing urinalysis, you have to inform your doctor if you are taking a particular supplement or if you are under a maintenance drug. (5, 6)

proper way of collecting a urine sample

Image 3: The image shows the proper way of collecting a urine sample.

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Collecting a urine sample 

Urinalysis can be done at home using a urine strip test readily available in the leading pharmacy or in a laboratory setting. When performing the test in a laboratory setting, you will be given a sterile container to catch the urine sample.

The urine should be collected first thing in the morning. It is a must to obtain a clean-catch urine. It can be done through the following ways:

  1. Thoroughly clean the urinary opening. For women, the labia should be spread and cleaned from front to back. For men, the tip of the penis should be wiped by a sterile pad.
  2. Start urinating in the toilet and pass the collection container in the urine stream.
  3. Catch at least two ounces of urine into the container.
  4. Continue urinating into the toilet.
  5. Submit the urine sample to the lab for analysis. (4, 5, and 6)

A urine testing strip using a dipstick

Image 4: A urine testing strip using a dipstick.

Picture Source: encrypted-tbn0.gstatic.com

 

Checking for urine using a dipstick test

A dipstick is a thin plastic stick with a strip covered with chemicals. It is used to check urine at home. The dipstick is placed in the urine to check for any abnormalities. If a certain substance is present in urine the color of the chemical strip changes.

If you are going to compare the urine dipstick test to the conventional urine test, you will notice that the dipstick test is more convenient. It is also cost-effective and won’t require any special training. In just a few minutes, you will be able to find out the result. A urine dipstick test is usually performed in:

  • Urgent care facilities
  • Emergency departments
  • Doctor’s office

Although it is convenient to use a urine dipstick, there are some drawbacks. It might not always lead to accurate results because the color changes are time sensitive. If you are not going to analyze the result immediately, then the changes in the color of the strip yields to an inaccurate results.

The information that you will get from the urine dipstick test is only limited. It is more of a qualitative test than a quantitative one. (6, 7, and 8)how a chart for urine dipstick analysis test looks like

Image 5: This is how a chart for urine dipstick analysis test looks like.

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A chemical analysis of urine using a urine test strip

A urine test strip using a dipstick is one of the commonly used methods of checking the chemical components of urine. The strip has squares of different colors attached to it. The whole strip is dipped in the urine sample and you have to watch out for changes in colors of each square.

It would only take a few seconds to notice the changes in color. It is a must to observe the proper time of dipping and reading the result as too early or too long could lead to an inaccurate result.

The changes in the color of each square indicates a specific abnormality, which is caused by a particular chemical reaction. You have to compare the color in the test strip to the reference for color changes on the plastic bottle container.

Each square represents a particular component such as the concentration of urine, pH level, protein in urine such as albumin, glucose/sugar, ketones (a byproduct of fat breakdown), hemoglobin, leukocyte esterase/white blood cells, bilirubin, nitrite, and urobilinogen. (7, 8, and 9)

 

The advantages and disadvantages of a urine test strip

Advantages

  • It is convenient to use.
  • Easy to interpret
  • Cost-effective
  • The analysis can be done in just a few minutes of collecting urine.

Disadvantages

  • It might not always yield to accurate result as urine test using a test strip is time-sensitive.
  • It only shows limited information about the composition of urine.
  • A urine test strip is more of qualitative and not much on the quantitative information. (1, 9, and 10)

What is checked during urinalysis?

  1. Acidity of urine – The pH level of urine is checked to determine if you are suffering from urinary tract infection or kidney-related conditions.
  2. Urine concentration/specific gravity – it checks how concentrated the urine is. If the urine concentration is higher than normal, then it is an indicator that you are not drinking enough fluids.
  3. Protein – It is just normal to have a low protein in the urine. However, if there is a large number of protein in the urine, it is an indicator of a kidney-related problem.
  4. Sugar – if there is moderate to a huge number of sugar in the urine, it is indicative of diabetes. Hence, additional testing will be needed to confirm the condition of the patient.
  5. Ketones – Any amount of ketone in urine could be a sign of diabetes mellitus. Hence, additional testing is needed.
  6. Bilirubin – it is a byproduct of the breakdown of red blood cells. Bilirubin is carried in the blood and passed into the liver for excretion and become a part of the bile. If bilirubin is detected in urine, it might indicate a damage to the liver/liver-related diseases.
  7. Nitrites/leukocyte esterase – leukocyte esterase and nitrites are products of white blood cells and if they are detected in urine, it could be a sign of urinary tract infection.
  8. Blood – The presence of blood in urine can be very alarming. It could indicate a blood-related disorder, kidney or bladder stone, kidney damage, infection, or cancer in the kidneys or bladder. However, it is not an indicative sign. Additional testing should be done to confirm the diagnosis. (2, 4, 7, and 8)

 

Microscopic examination of urine

Drops of urine are examined under the microscope to check for the following:

  • White blood cells/leukocytes – It is a sign of infection
  • Red blood cells/erythrocytes – It could be a sign of a possible blood disorder, bladder cancer, or kidney-related diseases.
  • Yeast/bacteria – it could suggest an underlying infection.
  • Casts – It is a tube-shaped protein which could indicate an underlying kidney disorder.
  • Urinary Crystals – It could be an indicator of kidney stones. (3, 6, 9, and 10)

Cells that can be checked in urinalysis

  1. There are a number of cells that can be detected in a routine urine test. These include red blood cells, white blood cells, and epithelial cells.
    1. Epithelial cells – They are cell linings found in different parts of the body, specifically in the skin, vagina, ureter, urethra, and bladder. If there’s epithelial cells in urine, it could be associated with infection or inflammation of the bladder or urethra.
    2. Red blood cells/erythrocyte – It could indicate bleeding in the lower part of the urinary tract, especially in the ureter, urethra, and bladder. The naked eye can easily detect the presence of blood in urine through obvious changes in urine color. However, the color of urine can also be affected by recent food intake such as red-colored tea or consuming a huge amount of beet root. To be specific, you have to check the urine under the microscope. If there is microscopic hematuria, it could mean trauma to the urinary tract. It could also be related to serious medical conditions like the presence of kidney stones, bladder tumor, hemorrhage, or cancer of the kidneys.
    3. White blood cells/leukocytes – The presence of white blood cells in urine could indicate a urinary tract infection. The suspicion can be confirmed if aside from white blood cells, there are other components present like bacteria, nitrite, and leukocyte esterase. (1, 4, 6, and 8)

 

What to keep in mind when performing urinalysis?

  • A urine test is not a definite diagnosis of a particular condition. Although, it helps detect the presence of abnormalities in the body, it is not only the basis in diagnosing a particular condition. The doctor might require follow-up test to determine the right course of action.
  • Normally, you are allowed to eat and drink before urinalysis. However, you have to watch out what you eat, especially strong colored foods like beets and food dyes as they can significantly change the color of your urine.
  • If you are taking supplements, vitamins, and any other drugs, you need to inform your doctor right away as they could affect the result of the exam.
  • If you are having your menstrual period during the exam, you have to inform your doctor.
  • Make sure you submit a fresh urine sample.
  • If you are using a dipstick, make sure you dip the stick briefly and completely. The reading should be done within a few minutes. (6, 9, and 10)

References

  1. https://www.mayoclinic.org/tests-procedures/urinalysis/about/pac-20384907
  2. https://labtestsonline.org/tests/urinalysis
  3. https://emedicine.medscape.com/article/2074001-overview
  4. https://www.webmd.com/a-to-z-guides/what-is-urinalysis#1
  5. https://www.kidney.org/atoz/content/what-urinalysis
  6. https://www.medicinenet.com/urinalysis/article.htm
  7. https://www.healthline.com/health/urinalysis
  8. https://medlineplus.gov/urinalysis.html
  9. https://my.clevelandclinic.org/health/diagnostics/17893-urinalysis
  10. https://www.aafp.org/afp/2005/0315/p1153.html

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