Doctors order urine tests for kids to make sure that the kidneys and certain other organs are functioning properly, or when they suspect that a child might have an infection in the kidneys, bladder, or other parts of the urinary tract.
The kidneys make urine as they filter wastes from the bloodstream while leaving substances in the blood that the body needs, like protein and glucose. So when urine contains glucose, too much protein, or has other irregularities, it's usually a sign of a health problem.
A urinalysis is usually ordered when a doctor suspects that a child has a urinary tract infection or a health problem that can cause an abnormality in the urine. This test can measure:
the number and variety of red and white blood cells
the presence of bacteria or other organisms
the presence of substances, such as glucose, that usually shouldn't be found in the urine
the pH, which shows how acidic or basic the urine is
the concentration of the urine
Sometimes, when the urine contains white blood cells or protein, or the test results seem abnormal for another reason, it's because of how or when the urine was collected. For example, a dehydrated child may have concentrated urine (darker urine) or a small amount of protein in the urine.
But that may not necessarily mean that there's a health problem. Once the child is rehydrated, these "abnormal" results may disappear. Depending on the amount of protein or other cells in the urine, the doctor may repeat the urine test at another time, just to make sure that everything is back to normal.
In most cases, urine is collected in a clean container, then a small plastic strip that has patches of chemicals on it (the dipstick) is placed in the urine. The patches change color to indicate things like the presence of white blood cells or glucose.
Next, the doctor or laboratory technologist also usually examines the same urine sample under a microscope to check for other substances that indicate different conditions.
If either the urine dipstick test or the microscopic test shows white blood cells, red blood cells, or bacteria — which may mean that there's an infection in the kidneys or the bladder — the doctor may decide to send the urine to a lab for a urine culture to identify bacteria that may be causing the infection.
Getting a urine sample. It can be difficult to get urine samples from kids to analyze for a possible infection. That's because the skin around the urinary opening normally is home to some of the same bacteria that cause infections in the urinary tract. If these bacteria contaminate the urine, the doctors may not be able to use the sample to tell if there is a true infection or not.
To avoid this, the skin surrounding the urinary opening has to be cleaned and rinsed immediately before the urine is collected. In this "clean-catch" method, the patient (or parent) cleans the skin around the urinary opening. The child then urinates, stops momentarily (if the child is old enough to cooperate), then urinates again into the collection container. Catching the urine in "midstream" is the goal.
In some cases, like when the child is not yet toilet trained, the doctor or nurse will insert a catheter (a narrow, soft tube) through the urinary tract opening into the bladder to get the urine sample.
If you have any questions about urine tests, talk with your doctor.