Medical Content Created by the Faculty of the
Harvard Medical School
For a regular urinalysis, your urine is tested both chemically and by microscopic exam. Chemical examination uses a "dipstick" to reveal the pH (acidity) and concentration of your urine, while simultaneously testing for several chemicals at once. Some chemicals indicate that blood in general and white blood cells in particular might be present, a sign of a urinary infection, kidney stones, or other problems. Nitrite, a chemical produced by most bacteria, suggests a bacterial infection. Sugar in the urine is a sign of diabetes (high blood sugar), while chemicals known as ketones can indicate a diabetic complication. Protein in the urine can indicate kidney disease or impaired kidney function.
A microscopic examination is done after the urine is spun inside a tube in a centrifuge. This concentrates the solid particles at the bottom of the tube, so they can be studied more easily. Microscopic examination can show red blood cells, white blood cells, bacteria, crystals, skin cells that might have contaminated the sample, and, rarely, parasites in your urine. In some cases, the way the cells look offers your doctor clues about whether they entered your urine from the bladder or the kidney.