Crystals in Urine: Meaning and Causes

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  • 0:05 Crystal Production
  • 0:50 Crystalluria
  • 1:38 Types of Crystals
  • 4:39 Lesson Summary
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Lesson Transcript
Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

This lesson will go over some of the major types of crystals that can be found in urine, what they look like, and why they may occur. Find out as we take a look at uric acid, struvite, cystine, sulfur, and calcium oxalate crystals.

Crystal Production

Crystals are so beautiful. They come in many different shapes and sizes. They can come about through natural formations in the ground and can even be grown at home thanks to chemistry sets! Some people even believe that a Lebanese girl in the 1990s cried tears of crystals in a miraculous fashion. That was later proven to be a hoax, of course.

Nonetheless, it does point in the direction I want to take you. Crystals, actual crystals, can be produced by your body. That's no lie or a hoax either. Except they're not cried out of your body during a world-wide hoax; they're urinated out instead in an inglorious fashion.


Crystals in the urine is known as crystalluria. Sometimes crystals are found in healthy people and other times they are indicators of organ dysfunction, the presence of urinary tract stones of a like composition (known as urolithiasis), or an infection in the urinary tract. Some of these disease processes that are associated with these crystals will be the focus of this lesson.

Do bear in mind that the presence of crystals in the urine is not necessarily an indicator that they were present in the person's urinary tract as some crystals form (or precipitate) more so after urination due to changes in temperature and pH. pH, by the way, is a measurement of how acidic or alkaline something is.

Types of Crystals

Without further delay, let's get to our first set of crystals:

Uric acid crystals are crystals, of varying sizes and shapes, found in acidic urine. Shapes can resemble rhomboids, parallelograms, and rosettes. They tend to be amber in color and are an indicator of disease processes, such as acute uric acid nephropathy. This is a condition that develops as a result of certain cancer treatment strategies, which cause increased cell and tissue destruction, the release of a lot of uric acid thereafter, and subsequent obstruction of the kidneys with uric acid crystal overload. This eventually results in kidney failure.

Another type of precipitation that can be found during urinalysis are calcium oxalate crystals. These are a type of crystal that forms in acidic urine that comes in two main forms. The dihydrate form looks like an envelope under the microscope, whereas calcium oxalate monohydrate crystals look like dumbbells and are associated with kidney failure due to the consumption of ethylene glycol (which is known as antifreeze).

In fact, if you watch crime shows, you probably have heard of this. Doctors can tell if a person, dog, or cat has been poisoned with antifreeze by analyzing these unique-looking crystals. The criminals may hide the antifreeze, but medical testing will reveal all to everyone concerned.

In contrast to calcium oxalate crystals, struvite crystals are crystals that form in alkaline urine and are composed of magnesium, ammonium, and phosphate, and, therefore, are sometimes called triple phosphate stones. They look like coffin lids under the microscope and are sometimes associated with a bacterial urinary tract infection caused by urea-splitting bacteria.

Other crystals that can be found include cystine crystals, which are hexagon-shaped crystals typically found in acidic urine and that are associated with an inherited disorder. This disorder results in the inability of kidneys to reabsorb an amino acid called cystine, resulting in cystinuria, or the accumulation of cystine in the urine. Cystinuria also causes, not surprisingly over time, the formation of kidney and bladder stones.

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