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Medical Author:

Siamak T. Nabili, MD, MPH

Siamak T. Nabili, MD, MPH

Dr. Nabili received his undergraduate degree from the University of California, San Diego (UCSD), majoring in chemistry and biochemistry. He then completed his graduate degree at the University of California, Los Angeles (UCLA). His graduate training included a specialized fellowship in public health where his research focused on environmental health and health-care delivery and management.

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Medical Editor:

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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Microscopic urinalysis entails placing a few milliliters of the collected urine sample into a special test tube with a cap. The test tube is then spun down (centrifuged) for a few minutes. The liquid part of urine on the top (the supernatant) is discarded with only a drop or two remaining in the tube. The solid part at the bottom of the tube (urinary sediment) is then gently mixed with the few drops of liquid urine left on top of it. A drop of this mix is then transferred using a small pipette onto a thin glass slide and analyzed under the microscope.

The urinary sediment is analyzed to look for white blood cells, red blood cells, epithelial cells (cells that line the urethra or bladder), and bacteria in the urine. Under the microscope, an estimate of the number of these components is typically assessed and reported. The quantity of these cells may provide additional clinical information.

Other useful information detected by the microscopic urinalysis is the evaluation of cellular elements in the urine. These cellular elements may represent debris from the kidney cells due to injury, inflammation, or infection of the kidneys, and usually are formed in tube-like structures called casts. There are a number of different types of casts that may be detected in the urine, each suggesting certain possible kidney conditions.

Sometimes crystals can be seen in the urine under the microscope. Small amounts of crystals in the urine may be normal in healthy people. Some nonspecific crystals may be seen in urine as a result of the urine sample not being freshly analyzed (within 1-2 hours), being kept at a cold temperature, or from acidic (low pH) urine. In other instances, specific crystals may be detected in urine (crystalluria) as a result of different types of kidney stones. Some antibiotics and anti-viral drugs may also promote crystal formation in urine.

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