24-Hour Urine Collection Test - Indications, Procedure, Test Results, and Risks

Introduction:

The kidneys filter blood and are responsible for the formation of urine. Under normal conditions, 800 to 2000 milliliters of urine is produced daily if the person has a fluid intake of two liters. If the amount of urine produced is above or below this range, it is a sign of kidney disease. This 24-hour urine collection test aims to measure the quantity of urine produced and detect abnormalities in the appearance of urine. The urine after collection is sent to the lab for analysis.

What Is a 24-Hour Urine Collection Test?

A 24-hour urine collection test is done to check the condition of the kidneys. The urine mainly consists of water and electrolytes like sodium and potassium in the dissolved state. It also contains the waste products, urea, formed after protein breakdown, and creatinine, formed after muscle breakdown. If the kidneys are functioning well, urea in the urine lies in the range of 7 to 21 milligrams per deciliter and creatinine 0.9 to 1.4 milligrams per deciliter. If the level of urea goes above 50 milligrams per deciliter and creatinine above 5 milligrams per deciliter, it indicates the presence of a disease in the urinary system. So the reason the doctor recommends a 24-hour urine collection test is to detect the abnormalities present in the constituents of urine. The patient collects urine throughout the day in a container, and it is then sent to the laboratory for examination.

Why Does the Patient Need to Undergo a 24-Hour Urine Test?

The test aims to diagnose any problem associated with the kidneys or other organs of the urinary system. It is also done to measure proteins, minerals, hormones, and other substances present in the urine. For example, several disorders result in kidney disease, and the doctor recommends a 24-hour urine test in such conditions. The diseases are listed below:

• Uncontrolled Diabetes: Diabetes is a condition in which the blood glucose levels are high. If the condition is not managed, it can result in various complications, diabetic nephropathy being one of them. In this condition, there is a high amount of protein (albumin) present in the urine, which can cause kidney damage.

• Hypertension: High blood pressure or hypertension damage the blood vessels present in the kidneys and interfere with their filtration mechanisms. So one of the causes of kidney disease is hypertension.

• Polycystic Kidney Disease (PKD): It is a condition in which multiple cysts (fluid-filled sacs) are present on the surface of the kidneys. Due to this condition, the size of the kidneys increases, causing them to lose their function over time.

• Lupus Nephritis: It is an autoimmune disease in which antibodies attack the kidneys and damage them. Inflammation of the kidneys, hematuria (presence of blood in the urine), and impaired functioning of the kidneys are commonly seen in this disease.

• Urinary Tract Infection (UTI): It can occur in any organ of the urinary system (kidneys, ureters, urinary bladder, and urethra).

• Alport Syndrome: In this condition, kidney disease is accompanied by hearing and vision problems. The patient presents with blood in the urine and loss of kidney function over time.

• Pyelonephritis: It is a condition in which the inflammation of the kidneys occurs as a result of infection.

• Nephrolithiasis: It is a term used for kidney stones that form due to the accumulation of minerals present in the urine. The stones restrict the flow of urine and also cause kidney damage.

• Preeclampsia: It is a condition in which blood pressure becomes high in pregnancy and leads to severe complications. The presence of proteins in the urine (proteinuria) and kidney injury are the most common symptoms.

How Should the Patient Prepare for the Test?

The patient should prepare for the test in the following ways:

1. First, it is important to understand the procedure before it is performed so the doctor will explain it in detail to avoid any confusion.

2. The urine needs to be collected in the given containers and stored in a cool place, preferably in a refrigerator.

3. Avoid drinking coffee and alcohol during the test as it can interfere with the results.

4. The patient should inform the doctor about the medications he is taking. Multivitamins and drugs like Ibuprofen, Acetaminophen can interfere with the test results, and the doctor might ask the patient to stop them for a day.

5. The urine needs to be collected throughout the day (24 hours), so the patient should avoid traveling on that day. In addition, it becomes difficult to carry a container of urine while traveling.

6. Female patients need to inform the doctor if they are pregnant or expecting to be.

What Happens During the Test?

The test is usually done by the patient at home but can also be done in the hospital. The steps to be followed in the test are listed below:

• The patient is usually given two containers, one for collection and the other for urine storage.

• The test starts in the morning, and the patient needs to flush the first urine as it is not to be collected.

• The time starts after the first urine. The urine that the patient passes after the first needs to be collected and transferred to the storage container.

• Mark the time as the urine is collected, and one thing the patient needs to keep in mind is that the urine needs to be stored in a cool place, which can be a refrigerator or a cooler.

• The patient must try to urinate once after 24 hours to finish the test.

• After the urine has been collected and the time has ended, the container needs to be labeled and taken to the laboratory as soon as possible.

• The reports will be obtained after the analysis of urine is complete.

When Will the Patient Get the Test Results?

The test report is directly sent to the doctor who prescribed the test and consists of the urine components examined along with their reference range values. The components of the test are listed below:

1. Urine Volume and Creatinine Levels: The test report mentions the urine volume because if the urine collected is less than the normal range, it indicates kidney disease. Usually, the flow of urine gets restricted in the presence of stones. Creatinine is a waste product produced by the muscles and gets eliminated from the body through urine. If the creatinine is not expelled from the body in the required range, it can cause several diseases.

2. The pH of Urine: It is a critical indicator of kidney disease. If the pH of urine is acidic (below 7), the chances of formation of uric acid stones are maximum.

3. Sodium, Potassium, Calcium, and Magnesium Levels: It is important to maintain a balance between the levels of sodium, potassium, calcium, and magnesium. If sodium is not consumed through the diet, the calcium levels in the urine increase, resulting in hypercalciuria. Potassium levels in the urine help to check the functioning of the kidneys. If the potassium is present in excess, the kidneys are not functioning correctly because the kidneys maintain the potassium level. Magnesium helps prevent kidney stones. Calcium keeps the bones healthy, but if the levels exceed the normal range, it is indicative of a disease.

4. Citrate Levels: Citrate is an essential component of citrus fruits like oranges, lemons, and grapefruit. It should be consumed in sufficient amounts because it inhibits the formation of stones. In addition, citrate does not allow the crystallization of minerals in the urine, thereby preventing stone formation. Therefore, citrate levels are monitored and included in the 24-hour urine test.

5. Oxalate Levels: It is important to maintain optimum oxalate levels because if the person is suffering from kidney stones, the oxalate levels are usually high. About 40 to 50 milligrams of oxalate are usually found in the urine per day. Spinach, rhubarb, nuts, and chocolates are some of the sources of oxalates.

What Are the Risks of the Test?

The patient collects the urine in a container for 24-hours, so this test is usually done at home. However, certain factors cause variations in the test results. These factors are listed below:

• The patient must collect the urine each time he goes to the bathroom, but sometimes the patient might forget to collect the urine.

• The urine might spill out of the container if the lid is not closed or the container is not kept stable, leading to the loss of urine.

• The urine needs to be collected for 24 hours and not beyond that because that would result in excessive urine and variation in the test results.

• If the urine container is not kept in the refrigerator, bacteria accumulate in the urine resulting in variation in test results.

• Exercising at the time of the test can reduce the urine output.

Conclusion:

The 24-hour urine collection test helps to evaluate the health of the kidneys. It provides an overview of all the urine components and their average values. If any of the components is in excess or deficient, it indicates the presence of disease. So this test helps the doctor identify the condition affecting the urinary system of the patient and start the treatment accordingly. The patient must be explained thoroughly about the urine collection procedure to avoid any variation in the test results. If all the instructions are followed, accurate test results are obtained, and the treatment can be started at the earliest. So the patient should undergo this test and follow all the instructions given by the doctor.