Urinalysis is an examination of the urine that investigates the physical, chemical and microscopic characteristics of the urine, which is useful to in the diagnosis of various health conditions.
Purpose
Urinalysis is a routine medical exam that can screen for early signs of many health conditions, including diabetes and renal disease. It is often used for this reason during pregnancy of before a surgical procedure.
It can detect the presence of blood or other substances in the urine and confirm a diagnosis of urinary tract infection (UTI). It can also be useful to investigate the cause of symptoms such as abdominal or back pain.
Before Urinalysis
There are some food and medications that can interfere with the results of the urinalysis. As a result, these may be temporarily stopped shortly before the urine sample is taken. Medication that may have an effect include:
- Chloroquine
- Iron supplements
- Levodopa
- Nitrofurantoin
- Phenazopyridine
- Phenothiazine
- Phenytoin
- Riboflavin
- Triamterene
It is also important to ensure that patients get adequate fluid intake prior to the urinalysis examination. This helps to increase the ease when taking the urine sample.
Urinalysis Demonstration
Urine Sample
A sample of the urine is needed to perform urinalysis, which may be taken at home, at a medical clinic or in a hospital.
For a clean catch urine specimen, the patient is asked to urinate into a plastic cup in a private setting to fill the cup. It is important to ensure that the sample is not contaminated by the external genitals and surrounding area. Additionally, a mid-stream sample is also best, which is taken by urinating a small amount in the toilet balls and then taking the urine sample.
The sample should then be covered with a lid to be sent to the laboratory. It is important that hands are washed following urination.
The collection of the urine sample is not painful and is very similar to the normal urination process. For this reason, there are no risks or complications involved with the examination.
Laboratory Testing
A dipstick urinalysis uses a specialized plastic strip with a series of pads that change color according to certain chemical conditions. This indicates the concentration of specific substances in the urine quickly and simply.
The urine sample is sent to a laboratory where it can be examined for various relevant parameters including:
- Color
- Clarity
- Acidity
- Specific gravity
- Blood cells
- Glucose
- Protein
- Ketones
- Bilirubin
- Cells
- Crystals
- Casts
- Mucus
- Bacteria
Abnormal values for any of these values may suggest the presence of a health condition that may need treatment and should be investigated further.
Results
The results of the various parameters of the urinalysis may be indicative of certain health conditions.
In a normal urine sample of a healthy person hemoglobin, nitrites, red blood cells and white blood cells are not present in the urine. Likewise, glucose, ketones, protein and bilirubin are not detectable.
Abnormal results may be indicative of health conditions such as a urinary tract infection (UTI), kidney stones, uncontrolled diabetes or cancer of the urinary tract.
Follow-Up
When the results are received from the laboratory, there is usually a patient consultation to review the results and make any relevant recommendations.
If there are any abnormal results, additionally diagnostic testing methods are often required to confirm the cause of the abnormality. This may include blood tests, imaging tests such as computed tomography (CT) scans and magnetic resonance imaging (MRI) or other tests.
References
Further Reading
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