Clinical Significance of Various Crystals Found In Urine

Naturally, Urine is a solution that contains as many dissolved substances(solutes) eliminated by the body as waste chemicals. These solutes  have the abilities to form crystals especially at higher concentration that can equally increase or decrease the pH of urine from acid to base and  vice-versa.The condition of crystals in the urine is known as Crystalluria.The presence of these crystals doesn’t necessary means a disease condition but can be used as indicators to detect or suspect diseases conditions such as an organ dysfunction or failure,presence of urinary tract infections and many other metabolic complications.These crystal can be found in man as other animals.In pet,Veterinary physician usually diagnose cases such as urinary tract crystals in cats mostly crystals in cat urine,crystals in dog urine,bladder crystals or bladder stones and this goes same with humans.The following are  various crystal found in urine and their clinical Significance

Uric acid Crystals

These crystals are of varying sizes and shapes, They are mostly  found in acidic urine with pH below 7. Uric Acid crystals turn to  resemble rhomboids, parallelograms, or rosettes in shape with an amber  color. Uric acid is a product of the metabolic breakdown of purine nucleotides.Though they are seen in normal urine, They  also act as an indicator of disease processes, such as acute uric acid nephropathy or urate nephrolithiasis.

They are also involved in complication such as kidney stones, gout, chemotherapy, or tumor lysis syndrome.These crystals are also found in dog’s bladder and if these crystal stacks together(
urate uroliths),they can form life-threatening stones with the potential of blocking the urethra

Some symptoms related to kidney stones include severe abdominal, flank, or groin pain,nausea and blood in the urine(hematuria).People living with gout which is one of the most commonest cause of uric acid crystal accumulation in the joints
characterized by sudden, severe attacks of pain, swelling, redness and tenderness in the joints, often the joint at the base of the big toe.with symptoms that include burning pain, stiffness, and swelling in a joint,Intense joint pain and limited range of motion.

How to prevent gout is simply by drinking plenty of fluids to reduce uric acid.Limiting or avoiding alcohol,intake of meat and sea food.

Also read  Difference Between Fat-Soluble and Water-Soluble Vitamins

Gout medication or treatment for gout is mostly with nonsteroidal anti-inflammatory drugs (NSAIDs), steroids, or colchicine and taking vitamins for gout such as vitamin C

Calcium Oxalate Crystals

Calcium oxalate crystals are  mostly found in acidic, neutral or alkaline urine. These crystals are colorless when viewed microscopically and exist two forms of the calcium oxalate crystal:

Monohydrate and Dihydrate form.

The monohydrate calcium oxalate crystal is described as the “picket fence” form. These dumbbells shaped crystals are common in ethylene glycol toxicity.

The dihydrate form is octahedral or “envelope” shaped.

These crystals are heavily associated with kidney stones, which can form when too much oxalate  mostly found in foods like spinach,beetroot,potato chips,french fries and bran. Kidney stone symptoms include severe groin or abdominal pain, nausea, fever, and difficulty passing urine(dysuria). In some cases, calcium oxalate crystals can be caused by the ingestion of toxic substances such as ethylene glycol. 

Reduction of salt consumption and change in food dietary can greatly reduces excess Calcium oxalate.

Calcium oxalate crystals
Calcium oxalate crystals

Hippuric acid Crystals

These crystals are  found in healthy individuals urine and acid, neutral, or slightly alkaline urine but remains extremely rare. They may be either yellow-brown or colorless prisms, plates, or needle-like in shape. Hipurric acid crystals are often conglomerated into masses.

Hippuric acid crystals
Hippuric acid crystals

Triple Phosphate Crystals or struvite

Triple phosphate crystals or struvite stones form in alkaline urine and are composed of magnesium, ammonium and phosphate. Rectangular in shape or similar with the coffin lid. These are sometimes associated with a bacterial urinary tract infection(UTI) caused by urea splitting bacteria.

Triple phosphate crystal
Triple phosphate crystal

Calcium Carbonate Crystals

Calcium carbonate crystals can be yellow to colorless appearing as dumbells or spheres with radial striations, found in alkaline urine. They are usually large crystals and can be readily observed at low magnification.

In rare cases, calcium carbonate crystals  in urine could be  due to hypoparathyroidism. Possible Symptoms of this include tingling in the hands and muscle cramping.

This can be resolve by drinking more water, getting more calcium, and taking vitamin D supplements 

calcium carbonate crystals
calcium carbonate crystals

Calcium Phosphate Crystals

These colorless crystals have a shape-like blunt ended needles or prisms, rosettes. Calcium Phosphate Crystals can be found in neutral and  alkaline pH urine.Although their presence in urine can be normal,they are sometimes associated to kidney stone formation.

Calcium Phosphate Crystals
Calcium Phosphate Crystals

Ammonium Biurate Crystals

It generally appear as brown or yellow-brown spherical bodies with irregular protrusions resembling “throny-apples”. Found in alkaline urine but can also be found in healthy individual urine.

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Note that Sometimes, ammonium biurate crystals may appear because the urine sample is old or has been poorly preserved after sample collection. Because of this, recollecting the urine sample may be advised if these crystals appear for reliable diagnostics

Ammonium Biurate Crystals
Ammonium Biurate Crystals

Amorphous  Crystals

They are found in acidic urine and may appear pink on gross analysis and yellow microscopically. These crystals appear as granules in the urine sediment.

“Amorphous” crystals normally appear as aggregates of finely granular material without any defining shape at the light microscopic level. They are mostly  comprised of urates, phosphates or xanthine. They are usually small crystals that are usually only observed at high magnification (unless there are large amounts of them), i.e. they mimic bacteria.

Amorphous urates (Na, K, Mg, or Ca salts) tend to form in acidic urine and may have a yellow or yellow-brown color, rhomboid. Amorphous phosphates are similar in general appearance, but tend to form in alkaline urine and lack color and are Coffin-lid shape. Xanthine crystals are usually in the form of “amorphous” crystals. These crystals occur in Dalmations on allopurinol therapy for urate urolithiasis. Generally, no specific clinical interpretation can be made based on the finding of amorphous crystals. Small amorphous crystals can be confused with bacterial cocci in some cases, but can be distinguished by gram-staining. Degenerating crystals or cells can also resemble “amorphous” crystals.

Amorphous  Crystals
Amorphous  Crystals

Bilirubin crystals

These crystals are considered abnormal in urine. They are form from conjugated bilirubin.Bilirubin is made when the healthy destruction of red blood cells occurs. It’s passed through the liver and are needle-like to granular crystals that are yellow in color. They are frequently attached to the surface of cells. These crystals are seen in several hepatic disorders.

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High levels of bilirubin (hyperbilirubinemia) or bilirubin crystals(bilirubinuria) in your urine could indicate liver disease or poor liver function. Other symptoms may include nausea, pain, vomiting, jaundice and fever.

Bilirubin crystal in urine
Bilirubin crystal in urine

Cholesterol Crystals

It appear as colorless rectangular plates with a notch in one or more corners and  found  in both neutral and acid urine..These crystals are likely to appear after the urine sample has been refrigerated.

The appearance of cholesterol crystal is associated with the Nephrotic Syndrome.They may be caused by renal tubular disease, which can lead to renal failure if left untreated.

Cholesterol Crystals
Cholesterol Crystals

Cystine Crystals

They are flat colorless plates and have a characteristic hexagonal shape with equal or unequal sides. It is found in acidic urine that are associated with an inherited disorder.The condition that causes cystine to bind together and form the crystals is called cystinuria. The crystals,

Presence of cystine crystals represents a proximal tubular defect in amino acid reabsorption.

Cystine Crystals
Cystine Crystals

Leucine Crystals

They are Yellowish-brown spheres with concentric circles with radial striations found in acidic and neutral urine. Leucine crystals may be seen in liver disorders in which amino acid metabolism is impaired.

Leucine Crystals
Leucine Crystals

Tyrosine Crystals

They  appear as colorless/yellow fine needles in acidic and neutral urine. Tyrosine crystals may be seen in tyrosinemia and in certain liver disorders in which amino acid metabolism is impaired

Tyrosine Crystals
Tyrosine Crystals

Sulfanomide Crystals

They are flat needles, sheaves of small needles or as spheroids. Often brown in color. The presence of sulfanomide crystals usually indicates administration of the drug and not necessarily a pathological condition. However, their presence is also associated with kidney stone formation.

Sulfanomide Crystals
Sulfanomide Crystals

References :

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About the Author: Arthur Westmann

DEFFE ARTHUR (AMOEBAMANN) is the founder and author of MLTGEEKS and MLTEXPO.He’s from Cameroon and is currently a Final year State Medical Laboratory Technician (MLT MA). Beyond lab works, he’s a passionate internet user with a keen interest in web design and blogging. Furthermore He likes traveling, hanging around with friends and social networking to do in his spare time.

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