- What is a 24-hour Urine Test?
- When is a 24-hour Urine Test performed?
- What preparation is needed for a 24-hour Urine Test?
- How is a 24-hour Urine Test performed?
- How are the results of a 24-hour Urine Test interpreted?
It is a lab test in a urine sample collected for 24 hours to evaluate renal function. Urine is composed of water and dissolved ingredients, such as sodium, potassium, urea, creatinine and other chemical compounds. Abnormal concentrations of these substances found in a 24hour sample may indicate a specific disease or disorder.
There are many diseases that may cause renal impairment. This impairment may be either permanent or transient, either acute or chronic. The test helps the physician evaluate the severity of the condition and, in some cases, will give information on its prognosis. Medical conditions that may cause renal impairment and require 24hour urine collection are:
- Diabetic nephropathy. It may occur as a result of chronic uncontrolled diabetes, which in the long run may cause permanent renal impairment.
- Hypertension. High blood pressure which cannot be regulated, in the long run cause permanent renal impairment.
- Lupus. It is an autoimmune disease, which afflicts the kidneys, skin, joints and nervous system.
- Frequent urinary tract infections (with renal involvement)
- Chronic urinary tract obstruction.
- Nephritic syndrome. It is a group of symptoms associated with many causes. It is characterized by proteinuria, high cholesterole levels and tissue oedema.
- Polycystic Kidney Disease (PKD). It is a genetic disorder, in which many cysts (fluid-filled sacs) develop in the kidneys.
- Cystinosis. It is a hereditary renal disease, in which the abnormal accumulation of a specific protein in the kidney causes renal impairment.
The above medical conditions are indicative, but there may also be other reasons that will lead the physician to order a 24hour urine sampling.
Your physician will explain the procedure and answer any potentially occurring questions you may have. In general, you should be aware of the following:
- No special preparation is usually needed (e.g. no fasting).
- You may be instructed to start sampling at a specific time point.
- If possible, choose a 24hour period during which you will be at home to avoid transferring the urine sample.
- In case of established or suspected pregnancy, inform your physician.
- In special cases, your physician may ask for specific preparation.
In addition, you have to make sure that you follow the conditions below:
- Make sure to collect the ENTIRE urine output. DO NOT MISS any part of the urine output.
- DO NOT collect urine beyond the 24hour period.
- Make sure there is no urine leakage from the collecting container.
- Keep the urine sample in a cool place.
- Try to be calm. Avoid acute anxiety.
- Avoid intense physical exercise.
For proper urine collection, follow the steps below:
- You will be given a big collecting container to store the urine. Also, a smaller one, in which you will urinate and then transfer the urine to the bigger one.
- It is recommended to start collecting urine in the morning. Note down the time of your first urination.
- Keep the big collecting container in a cool place, preferably in the fridge.
- Try to have your last urination 24 hours after the onset time (at the same time), so as to complete the full 24hour collecting procedure. If this is not possible, there is no problem.
- As long the procedure of urine collection has been completed, take the container with the urine sample to the laboratory.
- Depending on your health condition, you may be asked to collect samples on consecutive days. In such a case, you have to be cautious to collect urine samples in separate collecting containers (one container for every 24hour period sample).
The normal urine output produced by an adult every 24 hours is about 800-2.000ml/ day (with fluid intake of about 2lt/day). Normal values for every substance measured may have small differences from lab to lab. Should values be found abnormal, your physician will give you additional instructions and discuss therapeutic options.