Having a health problem can be a harrowing experience, especially when a person does not know exactly what the problem is. The kidneys, which filter all of the body's blood to process out waste and extra water, can be subject to many problems. The medical word associated with the kidneys is “renal,” which is derived from the Latin word for “the kidneys.” A variety of renal tests can be employed to check the kidneys’ function. Renal tests are usually non-invasive procedures, like a blood or urine test, or more advanced digital imaging tests, like a CT scan.
The first renal test that is usually administered is either a blood or urine test. Blood renal tests measure the amounts of certain minerals and organisms present in the blood to determine if the kidneys are functioning properly. An excess amount of creatinine is one of the first signs of kidney disease. Excess nitrogen, a common ingredient in urea, is also a sign that the kidneys cannot filter out waste properly. Calcium, phosphorus, potassium and sodium are also routinely checked in a blood renal test.
Urine tests can be basic or more advanced. For example, if a urine sample is collected, white blood cells and the amount of sodium are usually measured and analyzed in conjunction with any other renal tests administered, and results are compared against a person's symptoms. A 24-hour urine test may be ordered, in which urine is collected over a 24-hour period. This requires an overnight stay in a hospital, since a catheter must be inserted and all urine collected. A lack of proper urine production may be cause for worry, and a doctor might then order an entirely different type of renal test, called an imaging test.
Imaging tests can include a renal ultrasound, which uses high frequency sound waves to produce a real time photograph of the kidneys. A computerized tomography (CT) scan may be ordered, or a simple X-ray may be taken if the problem is thought to be a kidney stone, rather than renal disease or failure. A Magnetic Resonance Imaging (MRI) renal test may also be ordered, but this is usually only in cases where the other tests have failed to produce any viable answers concerning what may be causing a patient’s problem.
In the event that initial tests do not figure out the problem, a person may be referred to a kidney specialist, or nephrologist. A urologist may also be recommended. People experiencing pain or other symptoms should not try to diagnose themselves, but instead should consult a licensed medical professional to determine what the problem is and whether a renal test is needed.