Urine test is useful in providing information to assist in the monitoring, diagnosing and treatment of various diseases. This test helps in determining various components of urine which is produced by the kidneys as the waste product. Kidneys filter the blood to remove the unwanted substances (like minerals, fluids, waste material, etc.) and pour them in the urine, to be excreted. Thus the urine contains hundreds of different wastes from body. A clear picture of how well your kidneys are working, what you are eating and drinking, and how much exercise you are performing, which can affect your urine, can be obtained by undergoing urinalysis (UA). It is the portmanteau of two words: urine and analysis. UA is the most common method of the medical diagnosis for urine. It includes more than 100 different tests done on urine.
The target parameters in UA include color, specific gravity, clarity, odor, pH, proteins, enzymes, nitrites, glucose, ketones, leukocyte esterase (WBC esterase), bilirubin, free cortisol, and many more; some of these parameters are discussed below.
1. Color: an important parameter affected by various things like diet, exercising, drugs and diseases. The dark or light color of the urine indicates the level of the water in it. Yellow-amber color is the normal urine color. Medicines like vitamin B2 supplements can turn the urine color to bright yellow; foods like blackberries, rhubarb, or beets can turn urine red-brown; intake of phenols may turn urine to dark brown; jaundice or problems with bile metabolism turns urine to green; excessive intake of liquids turn urine colorless; and any other colors might be due to what you have consumed the last night.
2. Appearance: normally, the urine is clear. Cloudy urine means presence of crystals, blood, sperm, bacteria or blood.
3. Odor/smell: the urine scent can vary from odorless to a much stronger odor. But in general, the urine smell is not strong and has a nutty odor. A bad odor means an infection in urine due to E. coli; sweet and fruity odor means diabetes; and peculiarly strong odor is due to dehydration and concentrated fluids.
4. pH: it is a measure of how much the urine is acidic or alkaline. A value of 4 means strongly acidic, 7 means neutral, and 9 means strongly alkaline. Certain treatments or medications might change the pH of the urine, which can also be a cause of formation of kidney stones.
5. Specific gravity: the ion concentration of urine can be determined by specific gravity test. Protein amount in the urine can alter the specific gravity of the urine. 1.010 value means that the person is hydrated, while 1.020 value means dehydration.
6. Ions and trace metals
7. Blood cells: blood cells are not found in the urine. Injury to urethra, kidneys, ureters and bladder, any disease, or inflammation can lead to bloody urine. Vigorous exercising can also lead the blood to come in the urine.
8. Proteins and enzymes: generally, no proteins and enzymes are found in the urine. The proteins presence in the urine is confirmed when problems like kidney disease, pregnancy, and fever are determined; also in case of vigorous exercises, the proteins are found in the urine. Human chorionic gonadotropin (hCG) is a hormone found in the urine of pregnant women and in the urine of males having testicular cancer
9. Other molecules
10. Drugs: urine is tested o find the individual’s drug usage overtime.
11. Yeast cells or parasites: if they are found in the urine, this shows the presence of an infection.
For this test, 30--50 ml of urine sample is enough -- the morning’s first urine is preferred for UA. There is no special preparation like fasting is required for the test. But in some cases doctors may advise to fast if required.
The sample can be collected by following ways, prescribed by the doctor.
1. Clean-catch midstream one-time urine collection: in this method, the patient is advised to wash hands before collecting the sample; the lab technician provides a container to collect the sample; the patient needs to void the starting urine and collect the midstream urine without letting the container coming in contact with the genitals and voiding out the remaining urine; carefully close the container with the lid; and return it to the lab. Important to notice here is to not stop the flow of the urine while collecting the sample.
2. Double-voided urine sample collection: this method utilizes the technique that involves voiding the first urine of the day and then drinking water; after 30--40 minutes, collect the urine in the container and return the sample to the lab.
3. 24-hour urine collection: this process includes collection of the urine throughout the day in a big container of approx. 4 L capacity having a little amount of preservative. Start collecting your urine from the morning when you first urinate and repeat the process till the end of the 24-hour period. Keep the large container in the refrigerator and keep adding the urine by noting the time of the first and last urination. Now submit the sample to the lab.
There is no problem or discomfort in collection of a urine sample. There are also no risks related to collection of the urine. UA can be evaluated by mainly two means: physical appearance and microscopic analysis. UA test can also be performed by various means: routine UA or routine and microscopy (R/M) UA, urine test strips, and microscopic examination. Other methods include urine culture, urine electrolyte levels, X-rays of the kidneys, ictotest and intravenous pyelogram (IVP) – these tests are conducted when abnormal UA results are observed. Sometimes dip sticks are used to test the urine.
1. Urine dipsticks: this is a chemical analysis method of determining urine. This method exploits the technique of using a strip of plastic which has several squares made on it; each square measures different parameters of the urine. The urine is collected in a container and the entire strip is dipped into it. After few seconds to a few minutes, the color change occurs and every color change has a specific meaning and leads to important clinical decisions. If read too late or too early, the interpretation may be wrong and not accurate. The squares present on the strip measures various parameters of the urine: specific gravity, ketones, bilirubin, pH (acidity of the urine), leukocyte esterase, nitrite, urobilinogen, glucose, and protein.
2. Microscopic examination: this method uses microscope for examining the urine sample. It uses light microscope for this purpose. The urine sample is centrifuged, the top liquid part is discarded, the remaining solid portion is taken and mixed with the last drop of urine; and only one drop is taken and examined under the microscope while the sediment is examined under a low-power microscope. Low-power microscope helps in identifying the presence of any crystals, casts, squamous cells, etc. If high-power microscope is used, bacterial cells, clumps of cells, or other infectious cells present can be examined.
3. Macroscopic examination: this method involves examining the urine visually by noting its various characteristics like color, appearance, quantity, etc. Normal urine color is light yellow and clear. However, if cloudiness is observed with changes in the color and clarity, this suggests possibility of dehydration (dark color urine), liver disease (tea colored urine), infection (cloudy urine), muscle breakdown (orange or tea colored urine), etc. Apart from problems, medications can also be one of the reasons of change in the urine color.
4. Drug screening: the test is done to measure the amount of the drugs and their byproducts in the urine. In addition, this test is done for many purposes: school and employment screening, athletic screening, emergency room settings, and drug detoxification programs. This test helps in detecting cocaine, marijuana, amphetamines, metamphetamines, barbiturates, opiates, phenylcyclidine, and benzodiazepines.
5. Other common methods: other methods apart from UA include tests like pregnancy test, drug test, and specific chemicals test, which are not included in the routine UA.
6. Home test kit: this test is generally used by women to check if they are or not pregnant.
7. Other tests
This test is done on encounter of the following symptoms: colored urine, bad odor, flank pain, painful urination, red urine (blood in the urea, hematuria), fever, etc. All these symptoms mean a urine infection for which urinary tract is examined by undergoing the urine tests. To check the treatment conditions like diabetes, high blood pressure, kidney stones, etc., monitoring the disease progression and response to therapy, urine tests are done. The results of UA can have many interpretations. The more the atypical substances detected in the urine, the more likely it is to have a problem. During menstrual period and consuming medicines like tetracycline, the urine test is not performed. To lower the contamination chances, the doctor may use a urinary catheter to collect the sample. In case of serious illness where person is unable to provide the urine, doctors use catheter to collect their sample. In addition, a normal UA does not indicate that their there is no problem. Cases where person do not release significant amounts of substance or chemicals in the urine, the test result is normal but the problem exists. In early disease span, some people might not be urinating with the elevated atypical substances but during the day, which thus gets missed by the doctor.
The UA is a process of revealing a person’s health overview. A doctor correlates the person’s reports and the symptoms to conclude the result and findings, and look for the causes of abnormality in the results with other specific tests – comprehensive metabolic panel (CMP), urine culture, complete blood count (CBC), etc. and look for UTI