Urine Tests




Doctors order urine tests to make sure that the kidneys and other organs are functioning properly, or when they suspect that a child might have an infection in the kidneys, bladder, or 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 a child's urine contains protein and glucose or has other irregularities, it's usually a sign that there's some sort of infection or other health problem.

Urinalysis

A urinalysis is usually ordered when a doctor suspects that a child has a urinary tract infection. This urine test analysis can measure:
  • The number and variety of both red and white blood cells
  • The presence of bacteria or other organisms
  • The presence of substances, such as glucose, that the kidneys should have filtered out
  • 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 some other reason, it's because of how or when the urine was collected. For example, a dehydrated child may have a few white blood cells or a small amount of protein in the urine. But that may not necessarily mean that there's an infection or a health problem. Once the child is rehydrated, these "abnormal" results may disappear. Depending on the amount of protein or white blood cells in the urine, the doctor may repeat the urine test at another time, just to make sure that everything is back to normal.

How Is a Urinalysis Done?

In most cases, for urine testing, urine is collected in a clean container, then a plastic stick that has patches of chemicals on it (the dipstick) is placed in the urine. The patches change color to indicate certain things, like the presence of white blood cells or glucose.

The doctor or laboratory technologist also usually examines the urine under a microscope to check for other substances that indicate different conditions.

If a urinalysis shows white blood cells and 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 the bacteria.

Getting a Urine Sample. It can be difficult to get urine samples from kids that doctors can use and analyze. That's because the skin around the urinary opening normally is home to the same bacteria that cause infection inside the body. If these bacteria contaminate the urine, the doctors can't use the urine sample.

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, 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 will insert a catheter, (a narrow, soft tube) through the urinary tract opening into the bladder to get the urine sample.

Urine testing for kidney cells can help detect preeclampsia, a potentially serious condition involving high blood pressure and fluid retention during pregnancy, according to findings published in the American Journal of Obstetrics and Gynecology.

Podocyturia was present in all patients with preeclampsia. Compared with healthy women, those with preeclampsia showed significantly greater podocyturia. Moreover, podocyturia was a better predictor of preeclampsia than any of the blood tests the researchers examined. Further studies are needed, however, to determine exactly why greater numbers of kidney cells are released into the urine of women with preeclampsia, the team notes.
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