Introduction
Every day, your body removes waste from the blood through urine. During this process, different minerals and substances dissolve in urine and are excreted along with it. Sometimes, these can stick together and form tiny solid particles called crystals1.
Crystals in urine are very common and are found using routine urine tests. In most cases, a small amount of these crystals is completely normal and may not cause much problems. However, sometimes these crystals can be a sign of a problem. When they appear in large amounts or are of certain types, they may be linked to conditions like kidney stones, dehydration2, urinary tract infections, or metabolic disorders. If not noticed, they can grow or lead to complications1.
In this article, we will discuss the different types of urine crystals, their causes, symptoms, and when to worry. We will also cover how they are diagnosed and how to manage and prevent them.
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What Are Crystals in Urine?
Your urine normally contains waste substances like minerals, salts, and acids that are dissolved in liquid. These substances are filtered out of the blood by the kidneys and carried out of the body in urine. Most of the time, they remain dissolved and pass out easily. However, sometimes these substances stick together and form tiny solid particles called crystals. These crystals are usually formed in your kidneys1.
Urine crystals occur when the natural balance of chemicals in urine is disrupted. This can happen if you don’t drink enough water, which makes your urine more concentrated and allows particles to bind together more easily. Crystals can also form when the urine contains too many minerals or compounds. Changes in urine acidity, whether too acidic or alkaline, can also raise the risk1,2.
When this happens, the substances start sticking together and form crystals. Over time, they can grow bigger and may lead to problems like kidney stones.
Causes of Crystals in Urine
Crystals in urine can form due to several reasons that affect the balance of substances in the urine. These include the following.
- Dehydration: Not drinking enough water makes urine more concentrated1, which increases the chance of minerals sticking together and forming crystals.
- Dietary Factors: Following a diet high in salt, animal protein, or oxalate-rich foods (such as spinach, beets, and nuts) can raise the levels of crystal-forming substances in urine2,3.
- Urinary Tract Infections (UTIs): Some bacteria can change the chemical balance of urine, especially its pH, which can lead to the formation of specific crystals2.
- Medications: Certain drugs, such as Sulpha drugs or Acyclovir, can form crystals in urine or increase the concentration of substances that promote crystal formation2.
- Medical Conditions: Crystals in urine can be caused by or indicate many certain medical conditions. These include:
- Kidney stones: Formation of the crystals first, and if they continue to grow and combine, can develop into larger stones in the kidneys or urinary tract in weeks or months4
- Metabolic Disorders: Conditions like hypercalciuria (high calcium excretion in urine), hyperoxaluria (high oxalate excretion in urine), or hyperuricosuria (high uric acid excretion in urine) producing crystals2
- Gout: Increased uric acid production or changes in uric acid processing in the body causing crystal formation2
- Chronic diseases: Chronic diseases such as inflammatory bowel disease (IBD), chronic kidney disease, obesity, etc5,6.
Crystals in Urine Symptoms
Crystals in urine are often asymptomatic (no symptoms). But when symptoms occur, they may be associated with conditions such as kidney stones, urinary tract infections (UTIs), etc. The following are some symptoms that should not be ignored:
- Pain in the belly, abdominal region or back
- Pain seen spreading towards the groin (the area where the lower abdomen meets the upper thigh)
- Change in colour of the urine
- Presence of blood in the urine
- Occurrence of chills and fever
- Occurrence of nausea or vomiting4
- Persistent feeling of urination
- Difficulty in urinating (cannot urinate at all or very little urination)
- Pain when urinating
- Cloudy or foul-smelling urine1
Types of Crystals in Urine
There are several types of urine crystals. The following are the most common types of crystals in urine.
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1. Calcium Oxalate Crystals
Calcium oxalate crystals usually contain calcium oxalate, sometimes mixed with calcium phosphate. They are colourless, and shapes can be oval, biconvex, dumbbell-shaped, or long and rod-like may indicate a possible risk of kidney stone formation.
- Causes
- High oxalate levels due to diet (spinach, nuts, or chocolate) or certain medications.
- Increased absorption of oxalate due to certain intestinal conditions (intestinal surgery, short bowel syndrome, Crohn’s disease, coeliac disease, chronic pancreatitis, or use of orlistat)
- High calcium levels in the blood due conditions like hyperparathyroidism, hyperthyroidism, multiple myeloma, vitamin D toxicity, use of diuretics, vitamin D supplements, etc.
- Imbalance in calcium and oxalate levels in urine2.
They may also be found in normal urine in small amounts without any disease.
2. Calcium Phosphate Crystals
Contain crystals made of different forms of calcium phosphate such as calcium orthophosphate (amorphous phosphate), carbapatite, and brushite (dicalcium phosphate dihydrate). These crystals are usually colourless and may appear in different shapes depending on the type and may indicate a possible risk of kidney stone formation.
- Causes
- Changes in urine, especially alkaline due to conditions such as urinary tract infections or metabolic disorders.
- Increased calcium or phosphate levels in urine
- Conditions like primary hyperparathyroidism, where the parathyroid glands produce too much hormone, leading to increased calcium levels in the body and urine2.
In some cases, they may also be found in normal urine in small amounts without any disease.
3. Struvite (Triple Phosphate Crystals)
Crystals made of magnesium, ammonium, and phosphate. These are colourless and most commonly look like a coffin lid but can also appear as feather-like shapes, long prisms, and trapezoids.
- Causes
- Infection (UTIs) caused by urease-producing bacteria, such as Proteus, Klebsiella, Pseudomonas, Providencia, and some Staphylococcus species.
- High urine pH (alkaline due to the presence of ammonia in the urine)
- Infection-related kidney stone condition2.
4. Uric Acid Crystals
These include crystals made from four types of uric acid: amorphous uric acid, anhydrous uric acid (uricite), monohydrate, and dihydrate crystals. Among these, amorphous uric acid and uric acid dihydrate are most commonly seen.
- Causes
- Conditions such as gout, Lesch-Nyhan syndrome, tumour lysis and chemotherapy.
- Metabolic problems
- Lower urine pH (chronic diarrhoea, metabolic syndrome, and diabetes mellitus)
- Persistent acidic urine environment2
They may also appear even when blood uric acid levels are normal.
5. Other Rare Crystals
Some crystals are less common and are usually linked to specific genetic or metabolic conditions. These include:
- Cystine Crystals: Colourless crystals seen in a rare genetic disorder called cystinuria2
- Xanthine crystals: Does not have a specific shape, caused by a genetic disorder passed in families called as xanthinuria2
- Dihydroxyadenine (DHA) crystals: Brown or reddish-brown in colour caused by a genetic disorder called APRT (adenine phosphoribosyl transferase) deficiency2
How Are Crystals in Urine Diagnosed?
Crystals in urine are diagnosed using a combination of several tests, which help identify the type of crystals present and any underlying cause.
- Medical History: Your doctor may ask about symptoms such as pain, burning during urination, frequent urination, or blood in urine. They may also take a detailed history of your diet, daily fluid intake, medications you are taking, and any past or existing medical conditions. This information helps the doctor understand possible risk factors that may contribute to crystal formation in urine and decide what further tests are needed1,2,4.
- Urine Routine Examination (Urinalysis): This is the most common test used to detect urine crystals. Your doctor will collect the urine sample and then examine it under a microscope to check for the presence, type, and shape of crystals (composition). Crystals in urine test can also detect other findings like blood cells, bacteria, or protein that may suggest an underlying condition2.
- 24-Hour Urine Test: Your doctor might perform this test to measure calcium, citrate, oxalate, phosphate, sodium, sulphate, uric acid, creatinine, urea, and total urine volume. These values are important for assessing kidney stone risk, and each one is usually analysed in detail separately7.
- Blood Tests: Your doctor might recommend a blood test to measure levels of calcium, phosphorus, uric acid, and electrolytes in the body. These results help identify metabolic or kidney-related conditions that may contribute to crystal formation in urine4.
- Imaging Tests: Your doctor might perform several types of imaging tests, such as:
- Ultrasounds: A lower abdominal ultrasound can be done to check for the bladder wall, pouches (diverticula), etc., along with stones. Ultrasound for kidneys shows the position of the kidneys and can detect blockages or kidney stones8. However, crystals cannot be seen on ultrasound, and small stones in the lower ureter may sometimes be missed.
- X-rays: They use a small amount of radiation, which can slightly affect body cells. They can help find problems in the kidneys, ureters, or bladder that may affect urine flow such as stones8.
- CT scan (computer tomography): This scan can provide detailed 3D images if needed. It can detect kidney stones, blockages, infections, cysts, tumours, and injuries in the urinary tract. Low or ultra-low dose CT scans can also be used to check for urinary stones8.
Treatment Options for Crystals in Urine
A doctor should always guide treatment for crystals in urine. Hence, it is important to consult a doctor for proper care. He might suggest the following treatment options for crystals in urine.
General Measures
Your doctor might recommend the following measures along with medications:
- Fluid Intake: Drinking plenty of fluids helps dilute the urine, which reduces the concentration of substances that can form crystals and makes it easier for them to pass out of the body. However, people with kidney, heart, or liver disease need to be cautious, and increase fluid intake only if advised by the doctor, as excess fluids may worsen their condition or lead to fluid imbalance9.
- Diet: Dietary changes can help reduce the risk of crystal formation. This includes reducing salt intake, limiting excess animal protein, and avoiding high-oxalate foods like spinach, nuts, and chocolate, depending on the type of crystals3.
Medical Treatments
These include the following:
- Medications: Your doctor might prescribe the following medications for crystals in urine:
- Potassium citrate: Helps increase citrate levels and make urine less acidic (higher pH). Used to treat patients with low citrate levels in the urine, to help prevent certain types of crystals or stones (calcium crystals, cystine crystals and uric acid crystals (or stones).
- Thiazide diuretics: Help the body remove extra water and reduce calcium in urine.
- Allopurinol: Lowers high levels of uric acid in the body. Specifically for uric acid stones or crystals.
- Antibiotics: Kill or stop the growth of bacteria.
- Mercaptopropionyl glycine: Helps stop cystine from forming stones by making it easier to dissolve in urine10.
- Medical Procedures: Your doctor might perform other medical procedures if the crystals are quite large. These include:
- Shock wave lithotripsy: A procedure that uses sound waves to break kidney stones into smaller pieces so they can pass in urine. It is usually done under anaesthesia as an outpatient procedure but is less commonly used now.
- Cystoscopy and ureteroscopy: A procedure where a thin tube is passed through the urethra to look inside the urinary tract. If a stone is found, it can be removed or broken into smaller pieces. This is usually done under anaesthesia as an outpatient procedure.
- Percutaneous nephrolithotomy: A procedure to remove large kidney stones using a thin tube inserted into the kidney through a small cut in the back. The stone may be removed or broken into smaller pieces. It is done under anaesthesia and may require a short hospital stay.
- Hyperparathyroidism surgery: A procedure to remove the overactive parathyroid gland in people with hyperparathyroidism, a condition that causes too much calcium in the blood, which may develop calcium stones. This surgery can improve the condition and help avoid kidney stones10.
Treating Underlying Conditions: Your doctor suggests treating underlying conditions such as hyperparathyroidism, gout, diabetes, or other metabolic disorders because these conditions can increase certain substances in urine that lead to crystal formation2.
How to Prevent Crystals in Urine?
The following are some ways by which you can reduce the occurrence of crystals in urine.
- Increase Fluid Intake: Drinking plenty of water every day can keep the urine diluted and reduce crystal formation3.
- Limit Salt: Reduced intake of processed foods, fast food, and canned items can reduce sodium, which can increase the chance of kidney stones3.
- Limit Oxalate Foods: Reduce foods high in oxalates such as spinach, nuts, tea, peanuts, etc., as these can reduce the occurrence of crystals. Also, combining these foods with calcium-rich foods (such as milk or yogurt) may help reduce oxalate absorption and lower the risk of crystals. (if prone to calcium oxalate crystals)3.
- Reduce Animal Protein: Limiting red meat, poultry, fish, and pork can reduce uric acid and lower citrate levels3.
- Perform Regular Exercise: Performing exercises can reduce obesity, which is one of the causes of crystal formation.
- Maintain Proper Calcium Balance: Eat the right amount of calcium from foods such as dairy products, calcium-fortified cereals, breads, etc., as they help bind certain substances in the gut and reduce their entry into the kidneys3.
When to Consult a Doctor?
The following are symptoms you should not ignore if you have crystals in urine or if you develop any new symptoms.
- Severe pain in the side, back, or lower abdomen
- Burning or pain during urination
- Blood in urine
- Frequent urge to urinate with little urine output
- Cloudy or foul-smelling urine along with a fever
- Fever, chills, nausea or vomiting
- Difficulty passing urine or blockage of urine flow1
- Recurrent symptoms or repeated findings of crystals in urine test
Conclusion
Crystals in urine are common and often harmless when present in small amounts. However, in some cases, they may indicate dehydration, dietary issues, infections, or underlying medical conditions. Early detection through urine tests helps in proper diagnosis and management. With the right treatment, lifestyle changes, and good hydration, most cases can be effectively managed and avoided.
Also Read: The Fatty Liver Diet: Foods to Eat and Avoid to Reverse Fatty Liver Disease
Frequently Asked Questions (FAQs)
Can a UTI cause crystals in urine?Yes, a urinary tract infection (UTI) can cause crystals in urine, especially struvite crystals. This happens because certain bacteria change the urine environment, making it more likely for crystals to form2.
What are calcium oxalate crystals in urine?Calcium oxalate crystals in urine are tiny solid particles made from calcium and oxalate that can form when these substances become too concentrated in urine. They are the most common type of urinary crystals and may sometimes indicate a risk of kidney stones, but they can also appear in healthy people, especially if they are dehydrated or eat foods high in oxalate2.
What to drink for crystals in urine?Water is the best drink because it helps keep urine diluted and reduces the chance of crystal formation. You may also drink ginger ale or lemon-lime soda to maintain fluid intake11 but avoid too much sugary drinks as they can be dehydrating in summers.
Do urine crystals go away?Yes, small urine crystals can go away from your body through urine, with low or no pain at all1. However, large crystals might need further medical treatments10.
What foods should you avoid if you have crystals in your urine?If you are already diagnosed with crystals in urine, you are recommended to avoid foods rich in oxalate (nuts, peanuts, spinach, etc.), animal protein and uric acid (beef, chicken, eggs, shellfish, etc.), and salts (canned, packaged, and fast foods)3.
Are crystals in your urine bad?Crystals in urine (crystalluria) are not always harmful. While some might (small ones) go away on their own, some can indicate a health problem. They form when there are too many minerals and not enough water in the urine, causing the minerals to stick together1.
References
- Crystals in Urine. 2024. doi: https://medlineplus.gov/lab-tests/crystals-in-urine/
- Urinary Crystals Identification and Analysis. 2014. doi: https://www.ncbi.nlm.nih.gov/books/NBK606103/
- Eating, Diet, & Nutrition for Kidney Stones. doi: https://www.niddk.nih.gov/health-information/urologic-diseases/kidney-stones/eating-diet-nutrition
- Kidney Stones. 2024. doi: https://medlineplus.gov/ency/article/000458.htm
- Bianchi L, Gaiani F, Bizzarri B, et al. Renal lithiasis and inflammatory bowel diseases, an update on pediatric population. Acta Bio Medica Atenei Parmensis. 2018;89(9-S):76-80. doi:10.23750/abm.v89i9-S.7908: https://pubmed.ncbi.nlm.nih.gov/30561398/
- Jalal L, Jaffery Z, Nasir A, et al. Exploring the pathophysiological link between obesity and kidney stone formation: cost-effective dietary and lifestyle strategies for prevention. Annals of Medicine & Surgery. 2025;87(10):6521-6527. doi:10.1097/MS9.0000000000003691: https://pubmed.ncbi.nlm.nih.gov/41181498/
- Leslie SW, Sajjad H, Bashir K. 24-Hour Urine Testing for Nephrolithiasis: Interpretation and Treatment Guidelines. 2024. doi: https://www.ncbi.nlm.nih.gov/books/NBK482448/
- Urinary Tract Imaging. doi: https://www.niddk.nih.gov/health-information/diagnostic-tests/urinary-tract-imaging
- Healthy Hydration and Your Kidneys. 2024. doi: https://www.kidney.org/kidney-topics/healthy-hydration-and-your-kidneys
- Treatment for Kidney Stones. doi: https://www.niddk.nih.gov/health-information/urologic-diseases/kidney-stones/treatment
- Kidney stones – self-care. 2024. doi: https://medlineplus.gov/ency/patientinstructions/000135.htm
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