Crystals in urine are solid structures formed by minerals present in the urine, such as calcium oxalate, uric acid, struvite, and cystine. These crystals form due to an excess of minerals and a decrease in urine volume. While small amounts of urinary crystals can be normal, excessive amounts may indicate an underlying condition. Symptoms can include pain during urination, frequent urination, and cloudy or foul-smelling urine. Urinary crystals can increase the risk of kidney stones.
Detection of urinary crystals is possible through a urine test or urinalysis. Treatment options include lifestyle changes, medication, or surgery. Prevention strategies involve staying hydrated, maintaining a healthy diet, and treating any underlying medical conditions.
Type of urine samples:
- Random sample:
This is a diluted urine sample and may give an inaccurate interpretation of patient health. However, performing microscopy to evaluate white blood cells (WBC) or red blood cells (RBC) is still recommended for a more accurate assessment. - First Morning sample:
This is the best sample for microscopy and urinalysis. It is a concentrated urine sample because it remained in the urinary bladder overnight. This results in an increased concentration of analytes and cellular elements. Urine that has remained in the bladder for 8 hours is considered the first-morning sample. - Urine for sugar (Postprandial 2 hours):
A postprandial 2-hour urine sample is collected 2 hours after consuming a high carbohydrate diet. - Midstream clean catch urine:
This sample is needed for the culture and sensitivity testing of a urinary infection. The patient should clean the urethra, discard the first few milliliters of urine, and then collect the midstream urine in a sterile container. - 24 Hours of a urine sample
- In this case, discard the first urine and note the time.
- Then, collect all urine in a container for the next 24 hours, including the last sample.
- Refrigerate the collected sample.
- This 24-hour urine sample is needed for measuring urea, creatinine, sodium, potassium, glucose, and catecholamines.
- Suprapubic collection of the urine sample:
This procedure is performed on patients who cannot be catheterized and when a sample is needed for culture. The sample is collected using a needle. - Catheter collection of urine:
This procedure is performed on patients who are bedridden and cannot urinate. - Pediatric urine sample:
In infants, special collection bags are adhered around the urethra. Once the urine is collected in the bag, it is then transferred to a container.
Urine Crystals:
Crystals can be found in the urine of healthy individuals. They may be caused by minor issues, such as a slight excess of protein or vitamin C. Many types of urine crystals are relatively harmless.
Normal Crystals:
- Uric acid Crystals
- Calcium Oxalate Crystals
- Hippuric Crystals
- Calcium Phosphate Crystals
- Triple Phosphate Crystals
- Calcium Carbonate Crystals
- Ammonium Biurate Crystals
- Amorphus Crystals
Abnormal Crystals:
- Bilirubin Crystals
- Cholesterol Crystals
- Cysteine Crystals
- Leucine Crystals
- Tyrosine Crystals
- Sulfa Crystals
- Indinavir Crystals
Normal Crystals
1. Uric acid Crystals:
Urate crystals can form when there are high levels of uric acid in your blood. Your body produces uric acid during the breakdown of purines, which are substances found naturally in your body.
2. Calcium Oxalate Crystals:
Calcium oxalate crystals can be found in individuals with acidic, neutral, or alkaline urine. These crystals appear colorless when viewed under a microscope. There are two forms of calcium oxalate crystals:
- Monohydrate form: This form is described as the “picket fence” shape, resembling dumbbells. It is common in cases of ethylene glycol toxicity.
- Dihydrate form: This form is octahedral or “envelope” shaped.
These distinctions in crystal forms can provide insights into possible underlying conditions or exposures affecting the individual’s urinary tract health.
3. Hippuric Crystals :
Hippuric acid crystals are typically found in acid, neutral, or slightly alkaline urine. These colorless crystals can appear as prisms, plates, or needle-like shapes. They often conglomerate into masses, which can be observed under microscopic examination of urine samples.
4. Calcium Phosphate Crystals :
The description matches that of triple phosphate crystals, which are colorless and can appear as blunt-ended needles, prisms, or rosettes. They are commonly found in urine with a neutral to alkaline pH.
5. Triple Phosphate Crystals :
Triple phosphate crystals, also known as struvite crystals, indeed form in alkaline urine and are composed of magnesium, ammonium, and phosphate. They typically appear rectangular in shape or similar to coffin lids under microscopic examination. These crystals are often associated with bacterial urinary tract infections caused by urea-splitting bacteria, such as Proteus species.
6. Calcium Carbonate Crystals :
Calcium carbonate crystals are typically yellow to colorless dumbbells or spheres with radial striations. They are found in alkaline urine and are usually large enough to be readily observed at low magnification under a microscope.
7. Ammonium Biurate Crystals:
Ammonium urate (or biurate) crystals typically appear as brown or yellow-brown spherical bodies with irregular protrusions resembling “thorny apples”. These crystals are commonly found in alkaline urine.
8. Amorphous Crystals:
Amorphous urates are indeed found in acid urine. They may appear pink on gross analysis and yellow when viewed microscopically. These crystals present as granules in the urine sediment.
Amorphous phosphates, on the other hand, are found in alkaline urine. Microscopically, they appear as colorless granules.
Abnormal Crystals
1. Bilirubin Crystals:
Bilirubin crystals are abnormal crystals found in urine, formed from conjugated bilirubin. They typically appear as needle-like to granular crystals that are yellow in color. These crystals are often seen attached to the surface of cells. Bilirubin crystals indicate several hepatic disorders and are an important diagnostic indicator in clinical settings.
2. Cholesterol Crystals :
The description matches cholesterol crystals, which appear as colorless rectangular plates with a notch in one or more corners. They are typically found in acidic urine and their presence is associated with conditions like Nephrotic Syndrome.
3. Cystine Crystals :
Cystine crystals are indeed flat, colorless plates with a characteristic hexagonal shape, which may have equal or unequal sides. They are typically found in acidic urine and are associated with an inherited disorder known as cystinuria. The presence of cystine crystals indicates a proximal tubular defect in amino acid reabsorption, which is a key diagnostic feature in cases of cystinuria.
4. Leucine Crystals :
The description matches that of leucine crystals, which appear as yellowish-brown spheres with concentric circles and radial striations. These crystals are typically found in acidic to neutral urine. Their presence may indicate liver disorders where there is impaired amino acid metabolism.
5. Tyrosine Crystals:
Tyrosine crystals typically appear as colorless or yellow fine needles in acidic to neutral urine. They can be observed in conditions such as tyrosinemia and certain liver disorders where there is impaired amino acid metabolism.
6. Sulfa Crystals:
Sulfonamide crystals typically appear as flat needles, sheaves of small needles, or spheroids, often with a brown coloration. Their presence usually indicates recent administration of the drug rather than a pathological condition.
7. Indinavir Crystals :
Indinavir crystals can be readily observed in the urine sediment using routine light microscopy. Approximately 20% of an oral indinavir dose is excreted in the urine over the next 8 hours, with half of it as the intact indinavir molecule and the other half as one or more of its seven known metabolites, three of which are closely related structurally to the parent compound.
Crystals in the acidic urine :
| Name of crystals | pH | Shape | Color |
|---|---|---|---|
| Sodium urate | acidic (<acidic) | amorphous | Amorphous, or large granules |
| Uric acid | acidic <5.5 | rhombic, four-sided flat plates | yellow-brown |
| Amorphous urates | acidic >5.5 | amorphous or sand like | Microscopically yellow-brown and occurs in clumps |
| Calcium oxalate | acidic or alkaline | enveloped shaped, dumbbell-shaped | The colorless octahedral envelope or two pyramids joined at the base. |
| Cystine | acidic | hexagonal | Colorless |
| Cholesterol | acidic | rectangular, notched plates | Colorless |
| Tyrosine | acid/neutral | needles shape form clumps or rosettes | Colorless to yellow, needles |
| Leucine | acidic /neutral | spheres with a concentric circle or radial striations | yellow-brown |
| Bilirubin | acid | clumped needles or granular | yellow color |
| Sulphonamide | acid/neutral | Rosette form, needle, | colorless to yellow-brown |
| Ampicillin | acid/neutral | in needles form | colorless |
| Radiographic dye | acid | like cholesterol | colorless |
Crystals in alkaline urine :
| Name of crystals | pH | Color and shape |
|---|---|---|
| Amorphous phosphates | Alkaline | Granular |
| Triple phosphates | Alkaline | Colorless and prism-shaped like a coffin lid |
| Calcium phosphate | Alkaline | Colorless, flat rectangular plates or thin prisms often in rosettes |
| Calcium Carbonate | Alkaline | Small, colorless with a dumbbell or spherical shape, may occur in clumps and resemble amorphous material |
| Ammonium biurate | Alkaline | Yellow-brown color, thorny apples |
Pathophysiology
- There may be well-defined crystals or amorphous material in the urine sediment.
- The presence of crystals in the urine is called Crystalluria.
- When urine left at room temperature or refrigerated then urine becomes cloudy because of precipitation of crystals or amorphous material.
- These crystals are important in case of kidney stones.
- The stone formation may be without crystals in the urine or crystalluria may be without stone formation.
- Some of the crystals indicate some metabolic disorders like cystinuria or sulfa drug.
- Crystals are seen mostly in the concentrated urine.
- Crystals are divided into :
- Normal or abnormal
- In alkaline or acidic urine.
- Crystals found due to medication.
- Crystals found in acidic urine has pH of <6.5 and in alkaline urine pH is >7.0.
20 FAQs:
What are crystals in urine?
Crystals in urine are solid structures that form from minerals present in the urine.
What are the different types of crystals found in urine?
The most common types of crystals found in urine include calcium oxalate, uric acid, struvite, and cystine.
What causes crystals to form in urine?
Crystals form in urine when there is an excess of minerals or a decrease in urine volume.
Are crystals in urine normal?
Small amounts of crystals in urine are normal and can be caused by factors like diet and dehydration. However, excessive amounts of crystals may be a sign of an underlying condition.
What are the symptoms of crystals in urine?
Most people with crystals in urine do not experience any symptoms. However, in some cases, it can cause pain during urination, frequent urination, and cloudy or foul-smelling urine.
Can crystals in urine cause kidney stones?
Yes, crystals in urine can sometimes clump together and form kidney stones.
How are crystals in urine detected?
Crystals in urine can be detected through a urine test or urinalysis.
How are crystals in urine treated?
Treatment depends on the underlying cause of the crystals. It may involve lifestyle changes, medication, or surgery.
Can diet affect the formation of crystals in urine?
Yes, certain foods and drinks can increase the likelihood of crystal formation, such as those high in calcium, oxalate, and purines.
What are the risk factors for developing crystals in urine?
Risk factors include dehydration, a diet high in certain minerals, obesity, and certain medical conditions like gout and kidney disease.
Can children develop crystals in urine?
Yes, children can develop crystals in urine.
Are there any complications associated with crystals in urine?
Complications can occur if the crystals clump together and form kidney stones, which can cause pain and other symptoms.
Can crystals in urine be prevented?
Prevention involves staying hydrated, maintaining a healthy diet, and treating underlying medical conditions.
How long do crystals in urine take to form?
The time it takes for crystals to form in urine depends on a variety of factors and can vary from person to person.
Can medications cause crystals in urine?
Yes, certain medications can cause crystals to form in urine.
Can crystals in urine go away on their own?
In some cases, small amounts of crystals can go away on their own without treatment.
Can crystals in urine be a sign of cancer?
In rare cases, crystals in urine can be a sign of bladder or kidney cancer.
Can exercise affect the formation of crystals in urine?
Exercise can help prevent the formation of crystals by increasing urine volume and promoting hydration.
Can stress affect the formation of crystals in urine?
Stress can indirectly affect the formation of crystals by causing dehydration and other changes in the body.
How often should I get my urine checked for crystals?
If you have a history of kidney stones or other urinary issues, your doctor may recommend regular urine tests to check for crystals. Otherwise, it may not be necessary to get your urine checked unless you experience symptoms.
