Urinalysis: Purpose, Types, Preparation, Procedure, and Interpretation of Results

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Urinalysis is a diagnostic test that examines a person’s urine sample to detect and identify various substances such as glucose, protein, red blood cells, white blood cells, and bacteria. It is a common diagnostic tool used to evaluate various conditions such as urinary tract infections, kidney disease, and diabetes.

Definition of Urinalysis:

Urinalysis is a diagnostic test that examines a person’s urine sample to detect and identify various substances such as glucose, protein, red blood cells, white blood cells, and bacteria.

Also Known as:

Here are some alternative names for urinalysis:

Urinalysis
Urine test
UA (abbreviation for urinalysis)
Urine analysis
Urine examination
Urine Complete Examination
Urine C/E
Urine screening test
Urine dipstick test
Urine microscopy
Routine urine analysis
Comprehensive metabolic panel (CMP) with urinalysis
Basic metabolic panel (BMP) with urinalysis

Purpose of Urinalysis:

Here are some of the purposes of urinalysis:

To screen for various medical conditions, such as urinary tract infections, kidney diseases, and diabetes
To detect and monitor the progression of chronic kidney disease
To evaluate the effectiveness of treatment for certain medical conditions, such as urinary tract infections and kidney diseases
To monitor drug therapy and detect drug abuse
To screen for certain metabolic disorders, such as liver disease and porphyria
To assess overall health and hydration status
To detect the presence of illegal drugs in athletes or employees in certain professions
To perform pre-employment drug screening for certain jobs
To detect pregnancy through the presence of human chorionic gonadotropin (hCG) in the urine
To monitor for the presence of certain toxins, such as lead and mercury.

Types of Urinalysis:

Here are some types of urinalysis:

Routine urinalysis: This is the most common type of urinalysis and includes a physical examination, chemical analysis, and microscopic examination of the urine.
Microalbuminuria test: This is a specialized test that measures the level of a protein called albumin in the urine. It is used to detect early signs of kidney damage in people with diabetes.
Urine culture: This is a test that is used to identify the presence of bacteria in the urine and determine the specific type of bacteria causing an infection. It is often used to diagnose urinary tract infections.
24-hour urine test: This is a test that involves collecting all urine passed in a 24-hour period to evaluate kidney function and determine the levels of certain substances in the urine, such as creatinine and protein.
Pregnancy test: This is a test that is used to detect the presence of human chorionic gonadotropin (hCG) in the urine, which is a hormone produced during pregnancy.
Drug test: This is a test that is used to detect the presence of drugs or their metabolites in the urine. It is often used in workplace drug testing and forensic investigations.
Urine electrolyte panel: This test measures the levels of sodium, potassium, and chloride in the urine, which can be used to evaluate kidney function and diagnose certain conditions.
Urine protein test: This test measures the amount of protein in the urine, which can be used to diagnose kidney disease, diabetes, and other conditions.
Urine cytology: This is a test that involves examining the urine sample under a microscope to detect and identify abnormal cells that may indicate cancer or other abnormalities in the urinary tract.
Urine osmolality test: This is a test that measures the concentration of dissolved particles in the urine, which can help diagnose certain kidney disorders or dehydration.

Why Get Tested:

Here are some reasons why someone might need to get a urinalysis:

To detect or monitor a urinary tract infection (UTI)
To screen for or monitor kidney diseases such as chronic kidney disease or kidney stones
To evaluate kidney function before or during treatment with certain medications or chemotherapy drugs
To screen for or monitor diabetes or other metabolic disorders
To evaluate liver function or detect liver disease
To monitor drug use or therapy
To detect or monitor pregnancy
To screen for or monitor sexually transmitted infections (STIs)
To evaluate the overall health status of a patient
To diagnose or monitor certain types of cancer, such as bladder cancer

When to get tested:

Here are some situations when a doctor may recommend a urinalysis:

If a person has symptoms of a urinary tract infection (UTI), such as pain or burning during urination, frequent urination, or cloudy or foul-smelling urine.
If a person has symptoms of kidney disease, such as fatigue, swelling, high blood pressure, or changes in urination habits.
If a person has diabetes or other metabolic disorders that require monitoring of urine glucose or ketones.
If a person has liver disease or other conditions that affect the urinary system, such as prostate enlargement or bladder cancer.
If a person is taking medications that can affect the kidneys, such as certain antibiotics or chemotherapy drugs.
If a person is pregnant or planning to become pregnant.
If a person has a history of sexually transmitted infections (STIs) or is at risk of contracting an STI.
If a person is undergoing a routine health checkup and their doctor wants to evaluate their overall health status.
If a person has a family history of kidney disease or other urinary system disorders.
If a person is experiencing unexplained symptoms or has abnormal results on other tests that suggest a problem with the urinary system.

Type of urine samples:

Random sample:
This is a diluted urine sample and may give an inaccurate interpretation of patient health. But is best to do microscopy to evaluate WBC or RBC.
First Morning sample:
This is the best sample for microscopy and urine analysis. This is the concentrated urine because of urine remained throughout the night in the urinary bladder. This will contains an increased concentration of analytes and cellular elements. Urine must have remained in the bladder for 8 hours is considered as the first-morning sample.
Urine for sugar (Postprandial 2 hours):
Postprandial 2 hours sample collected after 2 hours of high carbohydrate diet.
Midstream clean catch urine:
This sample is needed for the culture and sensitivity of urinary infection. The patient is advised to clean the urethra, then discard the first few mL of urine. Now midstream of the urine is collected in the sterile container.
24 Hours of a urine sample
- In this case, discard the first urine and note the time.
- Now collect urine in the container for 24 hours and put the last sample in the container.
- Refrigerate the sample.
- This 24 hours samples are needed for measuring urea, creatinine, sodium, potassium, glucose, and catecholamines.
Suprapubic collection of the urine sample:
This is done in the patients who cannot be catheterized and the sample is needed for culture. This sample is collected by the needle.
Catheter collection of urine:
This is done by patients who are bedridden and can not urinate.
Pediatric urine sample:
In infants, special collection bags are made adherent around the urethra. Then urine is transferred to a container.

Preparation for Urinalysis Test:

Here are some general preparation tips for different types of urinalysis tests:

Routine urinalysis: Typically, no special preparation is needed for a routine urinalysis. However, it is important to follow any instructions provided by your healthcare provider regarding the collection and handling of the urine sample.
Microalbuminuria test: In some cases, you may be instructed to avoid eating or drinking certain substances before the test. Your healthcare provider may also recommend that you collect your urine sample at a specific time of day, such as first thing in the morning.
Urine culture: Before the test, your healthcare provider may ask you to clean your genital area with a special wipe or solution to reduce the risk of contamination. It is also important to collect a clean-catch urine sample, which involves cleaning the genital area and collecting the urine midstream.
Urine cytology: In some cases, you may need to avoid taking certain medications or supplements before the test to reduce the risk of false-positive results. Your healthcare provider may also recommend that you collect your urine sample at a specific time of day.
24-hour urine collection: Your healthcare provider will provide specific instructions for collecting and storing your urine sample over a 24-hour period. This may include instructions for avoiding certain foods, medications, or activities during the collection period.
Pregnancy test: Typically, no special preparation is needed for a pregnancy test. However, it is important to follow the instructions provided by the test manufacturer or your healthcare provider regarding the collection and handling of the urine sample.
Drug testing: Depending on the type of drug test, you may be instructed to avoid certain foods or medications before the test. Your healthcare provider may also provide instructions for collecting and handling the urine sample to reduce the risk of contamination or false-negative results.
Urine osmolality test: Typically, no special preparation is needed for a urine osmolality test. However, it is important to follow any instructions provided by your healthcare provider regarding the collection and handling of the urine sample.

Urine Sample Collection Guidelines:

Here are some general guidelines for collecting a urine sample for urinalysis:

Follow any specific instructions given to you by your healthcare provider. They may have specific guidelines for collecting and handling the urine sample based on the type of test being performed.
Make sure the collection container is clean and sterile. You can obtain a collection container from your healthcare provider or purchase one from a pharmacy.
Wash your hands thoroughly with soap and warm water before collecting the urine sample.
If you are a woman, clean your genital area with a special wipe or solution provided by your healthcare provider. If you are a man, wipe the tip of your penis with a clean, damp cloth.
Start urinating into the toilet, then move the collection container under the stream of urine to collect a midstream sample. This helps reduce the risk of contamination from bacteria or other substances on the skin or in the first part of the urine stream.
Collect at least 30-60 mL (about 1-2 ounces) of urine in the container, or as instructed by your healthcare provider.
If you are collecting a 24-hour urine sample, your healthcare provider will provide specific instructions for how to collect and store the urine over a 24-hour period.
After collecting the urine sample, seal the container tightly and label it with your name, the date, and the time of collection.
If you are unable to provide a midstream sample or have difficulty collecting the sample, contact your healthcare provider for further instructions.
Make sure to transport the sample to the laboratory or healthcare provider’s office as soon as possible, ideally within 1-2 hours after collection, or as instructed by your healthcare provider. Refrigerate the sample if you are unable to transport it immediately.

Result Interpretation of Urinalysis:

Interpreting the results of a urinalysis can be complex and depends on the type of test being performed. Here are some general guidelines for interpreting the results of a routine urinalysis:

Color : Normal urine should be pale yellow to amber in color. Abnormal colors, such as red, orange, or brown, may indicate the presence of blood or other substances in the urine.
Appearance : Normal urine should be clear and transparent. Cloudy or turbid urine may indicate the presence of bacteria, pus, or other substances in the urine.
Specific gravity: This measures the concentration of urine and can be an indicator of hydration status. Normal values range from 1.005 to 1.030. Low values may indicate overhydration or kidney problems, while high values may indicate dehydration or kidney problems.
pH: This measures the acidity or alkalinity of urine. Normal values range from 4.6 to 8.0. Low values may indicate acidic urine, which can be caused by certain medications or kidney problems. High values may indicate alkaline urine, which can be caused by certain medications or kidney problems.
Protein: Normal urine should contain very little or no protein. The presence of protein in the urine may indicate kidney problems, such as glomerulonephritis or nephrotic syndrome.
Glucose: Normal urine should not contain glucose. The presence of glucose in the urine may indicate high blood sugar levels, which can be a sign of diabetes or other metabolic disorders.
Ketones: Normal urine should not contain ketones. The presence of ketones in the urine may indicate that the body is using fat for energy, which can be a sign of diabetes or other metabolic disorders.
Blood : Normal urine should not contain blood. The presence of blood in the urine may indicate a urinary tract infection, kidney stones, or other problems.

It is important to note that interpretation of urinalysis results should always be done in the context of the individual’s overall health status and other diagnostic tests. Consult with your healthcare provider for a full interpretation of your urinalysis results.

Physical Examination:

Here is a list of the physical examination of urine:

Color : The color of urine can vary from pale yellow to amber. Abnormal colors may indicate certain health conditions, such as dark brown or black urine indicating liver disease or red or pink urine indicating the presence of blood.
Appearance : The clarity of urine refers to how clear or cloudy it appears. Normal urine is usually clear, but cloudy urine may indicate the presence of particles or cells, such as white blood cells or bacteria.
Odor: Normal urine has a slightly aromatic odor that is not unpleasant. A strong or unpleasant odor may indicate the presence of certain health conditions, such as an infection or metabolic disorder.
Foam: A small amount of foam on the surface of urine is normal. However, excessive foam may indicate the presence of protein in the urine.
Volume: The volume of urine passed may vary depending on hydration status, but a normal adult typically produces between 800 and 2000 milliliters of urine per day.
Sediment: Sediment refers to any particles or cells that may be present in urine, such as red or white blood cells, bacteria, or crystals.

Chemical Examination ( Dipstick test ):

Here is a list of the chemical examination of urine:

Protein: Protein is not normally present in urine, but small amounts may be found. Excessive protein in urine can indicate kidney damage or disease.
Glucose: Glucose is not normally present in urine, but may be found in individuals with high blood sugar levels, such as those with diabetes.
Ketones: Ketones are produced by the body when it breaks down fat for energy instead of glucose. Ketones in urine may indicate uncontrolled diabetes, a low-carbohydrate diet, or other metabolic conditions.
Bilirubin: Bilirubin is a waste product produced when red blood cells break down. Elevated levels of bilirubin in urine may indicate liver disease or other conditions that affect the liver.
Urobilinogen: Urobilinogen is a byproduct of bilirubin metabolism. Elevated levels may indicate liver disease or other conditions that affect the liver.
Blood : The presence of hemoglobin in urine may indicate the breakdown of red blood cells or other health conditions.
Nitrite : Nitrite is produced by certain bacteria that cause urinary tract infections. The presence of nitrite in urine may indicate a UTI.
Leukocyte esterase: Leukocyte esterase is an enzyme produced by white blood cells. Its presence in urine may indicate a UTI or other infection.
pH: The pH of urine is a measure of its acidity or alkalinity. Normal urine pH is typically between 4.5 and 8.0.
Specific gravity: Specific gravity measures the concentration of solutes in urine, and a normal range is between 1.005 and 1.030.

Microscopic Examination:

Here is a list of the microscopic examination of urine:

Red blood cells (RBCs): The presence of RBCs in urine may indicate a urinary tract infection, kidney stones, or other conditions that affect the urinary system.
White Blood cells (WBC): The presence of WBCs in urine may indicate a urinary tract infection, kidney infection, or other inflammatory conditions.
Epithelial cells: The presence of epithelial cells in urine may indicate inflammation or infection in the urinary tract.
Crystals: The presence of crystals in urine may indicate kidney stones or other conditions that affect the urinary system.
Bacteria : The presence of bacteria in urine may indicate a urinary tract infection.
Yeast: The presence of yeast in urine may indicate a fungal infection in the urinary tract.
Casts: Casts are tube-like structures that form in the kidneys and may indicate kidney disease or other conditions that affect the urinary system.
Parasites: The presence of parasites in urine may indicate a parasitic infection in the urinary tract.

Normal Urine Findings:

Here is a table of normal urine findings:

Characteristic	Normal
Color	Pale or yellow
Appearance	Clear
Odor	Mildly aromatic
Volume	1200 to 2000 ml/24 hours
pH	5 to 7
Specific gravity	1.001 to 1.035
Cast (hyaline)	0 to 5 / HPF
Red blood cells	≤ 3 / HPF
Blood	Negative Rarely 2 to 3 RBCs/HPF
White blood cells	≤2 to 5 HPF Male = 1 to 2 /HPF Female = 0 to 5 /HPF
Squamous epithelial cells	≤ 15 to 20 / HPF
Yeast	Negative
Bacteria	Negative
Protein	Negative
Glucose	Random sample = Negative 24 hours sample = 1 to 15 mg/dL
Keto n es	Urine = Negative
Bilirubin	Negative (o to 0.02 mg/dL)
Urobilinogen	Negative Random sample= <1 mg/dL 2-hour sample = <1 mg /2 hours 24- hours sample = 0.5 to 4.0 mg/dL
Nitrite	Negative
Albumin	10 to 100 mg /24 hours
Protein	Quantitative = negative Urine 24 hours sample: Adult male = 1 to 14 mg/dL Adult female = 3 to 10 mg/dL Child <10 years = 1 to 10 mg/dL
Calcium	Normal diet = 100 to 300 mg/24 hours Low-calcium diet = 50 to 150 mg/24 hours(Another source = 0.3 g/24 hours)
Sodium chloride	average 10 g /24 hours Patient with moderate to severe salt depletion = <10 mmol/L or <20 mmol/L /24 hours(Another source = 15.0 g/24 hours)
Sodium	Adult = 40 to 220 meq/24 hoursChild = 41 to 115 meq/24 hours
Potassium	Adult = 25 to 125 meq/ 24 hours Child = 10 to 60 meq/24 hours(Another source = 3.3 g/24 hours)
Magnesium	75 to 150 mg/24 hours(Another source = 0.1 g/24 hours)
Bicarbonate	Negative
Creatinine	Male = 20 to 28 mg/Kg/24 hours Female = 15 to 21 mg/Kg/24 hours(Another source = 1.5 g/24 hours)
Urea nitrogen	5 to 15 g/24 hours
Nitrogen	7 to 20 g/24 hours
Urea	10 to 35 g/24 hours(Another source = 25.0 to 35.0 g/24 hours)
Uric acid	With normal diet = 250 to 750 mg/24 hours With purine-free diet = <400 mg/24 hours With high-purine diet = <1000 mg/24 hours(Another source = 0.4 to 1.0 g/24 hours)
Urobilinogen	0.2 to 4.0 mg/24 hours
Chloride	Adult = 110 to 250 meq/24 hours Child: <6 years = 15 to 40 meq/24 hours Child: 10 to 16 years = 64 to 176 meq/24 hours

It’s important to note that normal ranges may vary slightly depending on the laboratory performing the test and the specific methods used for analysis. Additionally, the normal range may be different for certain populations, such as pregnant women or the elderly.

Limitations and Pitfalls of Urinalysis:

Here are some limitations and pitfalls of urinalysis:

False positives: Urinalysis can sometimes produce false-positive results, meaning that the test indicates a problem when there isn’t one. This can happen for a variety of reasons, such as contamination of the urine sample or medications that interfere with the test results.
False negatives: Urinalysis can also produce false-negative results, meaning that the test fails to detect a problem that actually exists. This can happen if the urine sample is not collected correctly, or if the levels of certain substances are too low to be detected by the test.
Lack of specificity: Some findings on a urinalysis may not be specific to a certain disease or condition, making it difficult to determine the underlying cause of the abnormal results.
Variability: Normal urine findings can vary depending on factors such as age, sex, diet, and physical activity, which can make it difficult to interpret the results of a urinalysis.
Incomplete information: A urinalysis is just one piece of information in a larger diagnostic puzzle, and additional tests may be needed to confirm or rule out certain diagnoses.
User error: Urinalysis requires careful attention to detail in collecting, storing, and analyzing the urine sample. Errors at any point in the process can lead to inaccurate results.

FAQs:

What is urinalysis?

Urinalysis is a laboratory test that examines the urine for abnormalities in appearance, composition, and concentration of substances.

How is a urine sample collected?

A urine sample can be collected by midstream clean-catch, catheterization, or urine collection bag.

How should I prepare for a urinalysis?

Follow your healthcare provider’s instructions, which may include fasting or avoiding certain medications before the test.

Can I eat or drink before a urinalysis?

It depends on your healthcare provider’s instructions. In some cases, you may be asked to fast for several hours before the test.

How is a urinalysis performed?

The urine sample is analyzed visually, chemically, and microscopically.

What can a urinalysis detect?

A urinalysis can detect the presence of various substances in the urine, such as glucose, protein, blood, bacteria, and crystals.

What are some common reasons for getting a urinalysis?

A urinalysis may be ordered to screen for a variety of conditions, such as urinary tract infections, kidney disease, diabetes, or liver problems.

How long does it take to get the results of a urinalysis?

Results are usually available within 24-48 hours.

Can a urinalysis be done at home?

Yes, there are at-home urinalysis kits available, but they may not be as accurate as a laboratory test.

How accurate is a urinalysis?

A urinalysis is generally accurate, but false positives and false negatives can occur.

What does it mean if my urine is cloudy?

Cloudy urine can be caused by various factors, such as dehydration, infection, or kidney stones.

What does it mean if my urine has a strong odor?

A strong urine odor can be caused by certain foods, medications, or dehydration, but it can also be a sign of infection or other medical conditions.

What does it mean if my urine is brown or dark in color?

Dark urine can be caused by dehydration, certain medications, or liver problems.

What does it mean if my urine is foamy?

Foamy urine can be caused by a variety of factors, such as dehydration, proteinuria, or kidney disease.

What is proteinuria?

Proteinuria is the presence of excess protein in the urine, which can be a sign of kidney disease or other medical conditions.

What are casts in urine?

Casts are cylindrical structures that can form in the kidney tubules and are excreted in the urine. They can be a sign of kidney disease.

What are crystals in urine?

Crystals in urine can be a normal finding, but they can also be a sign of certain medical conditions.

Can a urinalysis be used to detect pregnancy?

No, a urinalysis is not a reliable test for pregnancy. A pregnancy test is needed to confirm pregnancy.

Can a urinalysis be used to test for drugs?

Yes, a urinalysis can be used to test for certain drugs, such as opioids or amphetamines.

Can a urinalysis be used to test for sexually transmitted infections (STIs)?

No, a urinalysis is not a reliable test for STIs. Other tests, such as a urine culture or swab test, are needed to test for STIs.

Conclusion:

In conclusion, urinalysis is a valuable diagnostic tool used to assess the health status of an individual. It involves the physical, chemical, and microscopic examination of urine to detect any abnormalities in the urinary tract or other organs. The test is used to diagnose various conditions such as urinary tract infections, kidney diseases, liver diseases, diabetes, and many others.

Proper preparation and collection of urine sample are crucial for accurate results. Interpretation of the results should be done by a qualified healthcare professional who can provide appropriate treatment and management for any identified conditions. Although urinalysis has limitations and pitfalls, it remains an essential part of clinical diagnosis and management.

Possible References Used