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Urine test

life science Maturity 11-13 Next article →

A urine test is a medical procedure performed on a urine specimen. This analysis serves as a valuable diagnostic tool for healthcare providers. The composition of urine reflects the functioning of many internal body systems. It is especially useful for monitoring the kidneys and the urinary system. Because specimens are easy to obtain, they are frequently used in medicine.

Urine Quicktest
Urine Quicktest

Modern urine testing investigates various physical and biochemical properties. A routine urinalysis is a common starting point for many patients. This process examines the physical, chemical, and microscopic properties of the specimen. It can provide information about kidney function or suggest a urinary tract infection (UTI). Doctors also use urinalysis to screen for possible diabetes or liver disease. Some specialized tests, called urine cytology, analyze abnormal cells to help diagnose certain cancers.

Urine Quicktest
Urine Quicktest

Different types of tests target very specific biological markers. For example, a urine pregnancy test detects human chorionic gonadotropin, or beta-hCG. Point-of-care tests can also detect excreted drugs or their metabolites to screen for recreational drug use. To identify the specific bacteria causing a UTI, doctors perform a urine culture. This microbiological culture helps determine the exact bacterial species involved. Other tests check for organic acids or amino acids to screen for genetic disorders.

Urine cultured on Oxoid Brilliance UTI Agar plate
Urine cultured on Oxoid Brilliance UTI Agar plate

Medical professionals use many different metrics to assess health. They might measure urine creatinine or creatinine clearance to check kidney function. The albumin/creatinine ratio is used specifically to diagnose microalbuminuria. Doctors also look at urine osmolality and urine specific gravity to measure solute concentration. Electrolyte levels, such as sodium and potassium, are also measured. To distinguish between causes of metabolic acidosis, they may calculate the urine anion gap.

Urine Quicktest
Urine Quicktest

Collecting a specimen requires specific techniques depending on the desired test. A random urine sample can be collected at any time. However, a first morning specimen is often preferred for pregnancy screening and urinalysis. This is because the urine is typically more concentrated, which makes the test more sensitive. Some tests require a timed collection, such as a 24-hour collection. In these cases, a patient collects all urine into a container for a set period.

Trace metal-free 24 hour urine container
Trace metal-free 24 hour urine container

Special containers are used for certain measurements to ensure accuracy. For instance, a 24-hour container might be free of trace metals. This allows for the precise measurement of specific substances. When a microbiological culture is needed, the sample must not be contaminated. Doctors recommend a "midstream clean catch" for this purpose. The patient cleans the genital area and begins urinating into the toilet first. They then fill the specimen container before finishing urination in the toilet.

There are alternative methods for patients who cannot urinate voluntarily. Doctors may use a urinary catheter to obtain a sample. They can also perform suprapubic aspiration, which involves inserting a needle through the abdomen. For infants and young children, a bag can be attached to the genital region. However, this method carries a high risk of contamination.

Trace metal-free 24 hour urine container
Trace metal-free 24 hour urine container

The history of urine examination is quite long. People recognized the diagnostic value of urine in ancient times. Examination practices existed in Sumer and Babylonia as early as 4000 BC. Ancient Greek and Sanskrit texts also describe these types of examinations. Today, these ancient observations have evolved into highly sophisticated biochemical analyses. This allows doctors to understand complex systems like the adrenal glands through cortisol tests.

Urine cultured on Oxoid Brilliance UTI Agar plate
Urine cultured on Oxoid Brilliance UTI Agar plate
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File:Trace metal-free 24 hour urine container.jpg
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File:Urine cultured on Oxoid Brilliance UTI Agar plate.jpg
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