What do urine tests tell us?
This article:
- Reviews common urine collection methods
- Breaks down the types of tests that may be done on your urine
- Outlines what your results might reveal
Urine, produced by the kidneys, contains filtered water, electrolytes and cells, amongst other things. Testing urine allows your provider to see how your kidneys and urinary system are functioning or identify substances in your body [1]. Here we break down the most common types of tests done, how to provide accurate samples, and what they may reveal about your health.
Common urine samples and requirements for testing
Urinalysis
This test is done by peeing into a small sterile container. Filling the small container up approximately 3/4 of the way is generally considered a good sample size [1].
Clean Catch Midstream
The important aspect of this collection method is to ensure the urine is not exposed to external factors. Thus washing your hands, cleaning the genital area, then urinating a little before you start collection and keeping the lid as free from touching a surface is really important [1].
Double Voided Urine
Most important in this test is providing a sample of recently drunken fluids. Peeing, then drinking water and waiting 30–40 minutes to collect the sample is the most common method [1].
24-hour Urine Collection
Starting in the morning, your first pee does not get collected, however this time should be noted and urine collection commences afterwards. Each time you urinate afterwards, this should be collected in a large container provided to you [1].
For all samples it’s important that you do not contaminate the results as best as possible. This includes allowing toilet paper, menstrual blood, stool, or other foreign materials to enter the samples [1].
Common Tests Performed on Urine Samples
Once sent to the lab, here are the common things that laboratories are looking for within your urine samples.
Physical Examination
Colour — Detection of hydration status, kidney, liver, genetic diseases, diabetes or presence of blood. Normal results: Pale to dark yellow
Clarity — Determine presence of pus, blood, sperm, bacteria, yeast, crystals, mucus or parasites (such as STIs). Normal results: Clear
Odour — Foods and drugs may alter odour. Diabetes, Urinary Tract Infections (UTI)s, maple syrup disease will also alter the smell. Normal results: Slightly Nutty
Volume — Reported for 24-hour collection only. Determines amount of urine produced; too little or too much can indicate issues present. Normal results: 800–2,000 mL/day*
Chemical Examination
Specific Gravity — High results indicate dehydration, loss of fluid or substances in the urine (sugar or protein). Low results indicate dilute urine, indicating well hydrated, severe kidney disease or use of medications to increase urine production. Normal results: 1.005–1.030*
pH — Foods can affect urine pH level. High pH can be a result of vomiting, kidney disease, UTIs or asthma. Low pH levels can be caused by lung disease, uncontrolled diabetes, aspirin overdose, diarrhea, dehydration, starvation, consuming alcohol or antifreeze. Normal results: 4.6–8.0*
Bilirubin — Detection of bilirubin in urine is indicative of liver disease or biliary obstruction. Normal results: Negative
Glucose — Too much glucose in the urine may be caused by uncontrolled diabetes, an adrenal gland problem, liver damage, brain injury, certain types of poisoning, some types of kidney diseases, exposure to some IV fluids or in healthy pregnant women. Normal results: None or 60–830 mcmol/L in a 24-hour sample*
Blood — Additional studies are often required to determine the source of blood in urine. Normal results: Negative
Ketones — Ketones in the urine can mean uncontrolled diabetes, very low-carbohydrate diet, starvation or eating disorders, alcoholism, or drinking rubbing alcohol. Ketones are often found in the urine when a person does not eat (fasts) for 18 hours or longer. Low levels of ketones are sometimes found in the urine of healthy pregnant women. Normal results: None
Protein — Protein in the urine may indicate kidney damage, an infection, cancer, high blood pressure, diabetes, lupus, or kidney inflammation is present. Protein in the urine could also indicate heart failure, leukemia, poison (lead or mercury poisoning), or preeclampsia (if you are pregnant) exist. Normal results: None
Nitrite — A positive nitrite test is strongly suggestive of urinary tract infection. Normal results: ≥105 organisms/mL*
Leukocytes — Suggest infection present for example UTI, urethritis etc. Normal results: 10 or more leukocytes/hpf*
Microscopic Examination
White Blood Cells (WBC) — White blood cells (pus) in the urine may be caused by a UTI, bladder tumour, inflammation of the kidneys, lupus, or inflammation of the genitals. Normal results: Few to none
Red Blood Cells (RBC) — May be caused by kidney or bladder injury, kidney stones, UTI, inflammation of the kidneys, a kidney or bladder tumour, or lupus. Normal results: Few to none
Bacteria, Yeast, Parasites — Any can indicate a UTI. Normal results: None
Casts — Can indicate kidney inflammation or damage, metal poisoning (such as lead or mercury), heart failure, or a bacterial infection. Normal results: None
Crystals — Large amounts of crystals, or types of crystals, can indicate kidney stones, kidney damage, or problems with metabolism. Some medications or types of urinary tract infections can increase the number of crystals in urine. Normal results: A few
Epithelial or Squamous Cells — If present, the test should be re-administered. Normal results: None
Mucus — May indicate presence of pus or blood. Normal results: None
*Important to note that lab ranges often vary from lab to lab. Review your labs ranges to ensure misinterpretation is mitigated when reviewing your results.
Although this is a comprehensive look at urine testing, there are many other substances and tests that can be done on urine to detect substance use and abuse or detect various abnormalities or diseases. Make sure you ask your provider what the purpose of the test is so that you can anticipate what results you might see next time you provide a sample.
References
[1] Healthwise Incorporated, “Urine Test,” HealthLinkBC, 12 April 2017. [Online]. Available: https://www.healthlinkbc.ca/medical-tests/hw6580#hw6583. [Accessed 14 June 2018].
[2] Farlex, “Urine,” The Free Dictionary, 2009. [Online]. Available: https://medical-dictionary.thefreedictionary.com/urine. [Accessed 18 June 2018].
[3] Lexicomp, “Urinalysis,” 17 January 2018. [Online]. Available: http://online.lexi.com.myaccess.library.utoronto.ca/lco/action/doc/retrieve/docid/disandproc/3758765. [Accessed 14 June 2018].
