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What are kidney stones?

What are kidney stones?

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Stefano Mirabello Medical ReviewerGreen tick
Medically reviewed by Stefano Mirabello, BPharm and written by Rajive Patel, BPharm - Updated on 14 Dec 2022
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Table of contents
OverviewKidney stones – What are they?Types of kidney stonesWhat causes kidney stones?What are the signs of passing a kidney stone?How long does it take to pass kidney stones?Diagnosis of kidney stonesTreatment options for kidney stonesSurgery for kidney stonesSources

You’ve probably heard of kidney stones, but what exactly are they? Kidney stones medically known as nephrolithiasis are hardened deposits of minerals and acidic salts that form inside your kidneys. It is one of the most common urinary system disorders, affecting about 1 in every 10 people at some point in their lives. These small stones can cause immense pain as they try to pass through your urinary tract. In this blog post we’ll give you a basic overview of kidney stones: what they are, what causes them, and how they’re treated.

Kidney stones – What are they?

Kidney stones are small, hard deposits that build up in your kidneys. They occur when your urine contains more crystal-forming substances, such as calcium, oxalate and uric acid than the fluid in your urine can dilute. At the same time, your urine may not contain enough substances, such as citrate and magnesium, that would normally prevent crystals from forming. Kidney stones vary in size. A small stone may pass through your urinary tract on its own. Larger stones may get stuck along the way and cause a blockage that leads to pain, infection, or kidney damage.

Kidney stones usually first develop in your kidneys. As they grow, they may move down the tubes (ureters) that connect your kidneys to your bladder. If a kidney stone gets stuck in a ureter, it can block the flow of urine and cause severe pain in your lower abdomen or groin. As you drink fluids throughout the day, they travel through your urinary system and eventually make their way out of your body through your urethra, the small opening at the end of your urinary tract where urine exits your body.

Types of kidney stones

There are four main types of kidney stones, which are classified based on their chemical composition. The most common type is calcium oxalate stones, followed by uric acid stones, struvite stones and cystine stones.

Calcium oxalate stones are caused by too much calcium in the diet or by excess calcium in the blood. Uric acid stones are formed when there is too much acid in the urine. Struvite stones are caused by an infection in the kidney or urinary tract made up of magnesium and ammonium phosphate. Cystine stones are rare and occur in people with a genetic disorder called cystinuria.

What causes kidney stones?

There isn’t one specific cause of kidney stones; rather, there are a variety of different factors that can increase your risk. Some common causes include:

  • Dehydration: When your body doesn’t have enough fluids, it can lead to dehydration. When you’re dehydrated, your blood can become thick and sticky. This makes it harder for your kidneys to filter it. The waste products in your blood can then form crystals that become kidney stones. Kidney stones usually occur when you don’t drink enough fluids or when you lose too much fluid through sweating or vomiting. Factors that can increase your risk of dehydration include exercising in hot weather, having an illness that causes vomiting or diarrhoea, and taking certain medications, such as diuretics. Drinking plenty of fluids is the best way to prevent dehydration and kidney stones. Be sure to drink more when it’s hot outside when you’re sick, and while taking certain medications
  • Diet: Eating a diet that contains certain foods can increase your risk for kidney stones. For example, eating a lot of foods high in oxalates, such as spinach, rhubarb, and chocolate can cause kidney stones. Eating a diet high in animal protein, such as beef, pork and lamb, can also increase your risk. Animal protein increases the amount of uric acid in your urine. Uric acid is another substance that can form kidney stones. Drinking too much soda can also increase your risk because it contains phosphate
  • Family history: Kidney stones is a common condition that affects people of all ages. While the exact cause of kidney stones is not known, there are several risk factors that may contribute to their formation. One of these risk factors is family history. Studies have shown that people with a family history of kidney stones are more likely to develop them themselves. There are several theories about why this may be the case. One theory is that certain genes may make people more prone to developing kidney stones. Another theory is that people who have a family history of kidney stones may be more likely to eat a diet that promotes stone formation. Whatever the reason, it is clear that family history is an important risk factor for kidney stones. If you have a family history of kidney stones, you may be able to reduce your risk by drinking plenty of fluids and eating a healthy diet
  • Weight-loss surgery: People who have had weight-loss surgery are also at an increased risk for developing kidney stones because they often have unusually high levels of hormones that promote stone formation (such as vitamin D) and low levels of substances that prevent stone formation (such as citrate)
  • Medications: Certain medications can increase the risk of kidney stones. Medications that can lead to kidney stones include diuretics, calcium supplements, antacids and corticosteroids. Some anticonvulsants and antipsychotics can lead to dehydration, which can also increase the risk of stone formation. When these medications are metabolised by the body, they can increase the levels of calcium, oxalate and uric acid in the urine. This leads to the formation of crystals, which eventually grow into kidney stones
  • Certain medical conditions: While kidney stones can occur in anyone, there are certain medical conditions that make you more prone to developing them. One such condition is obesity. Obesity increases your risk of developing kidney stones because it alters the levels of hormones and minerals in your body, which can lead to the formation of stones. Another condition that makes you more prone to kidney stones is high blood pressure. High blood pressure can damage the kidneys, making it more difficult for them to function properly and filter out waste products. Other conditions, such as gout, renal tubular acidosis, diabetes and inflammatory bowel disease can also increase your risk

What are the signs of passing a kidney stone?

The first sign of passing a kidney stone is usually severe pain in your lower back or lower abdomen that comes in waves as the stone tries to pass through your urinary tract. Other symptoms of kidney stones may include blood in your urine (hematuria) difficulty urinating, cloudy or foul-smelling urine, frequent or persistent urinary tract infections, urinary urgency or frequency and nausea or vomiting.

If a kidney stone becomes lodged in the urethra, it can block the flow of urine and cause a urinary tract infection (UTI). Kidney stones vary in size. A small kidney stone may pass through your urinary tract on its own. A large stone may get stuck along the way and cause a blockage that leads to pain, infection or kidney damage.

How long does it take to pass kidney stones?

As mentioned earlier passing kidney stones can be a very painful experience. But how long does it actually take for the stones to pass? Unfortunately, there is no one-size-fits-all answer to this question.

The length of time it takes to pass kidney stones depends on a number of factors, including the size of the stone, the position of the stone in the kidney and the individual’s urinary tract anatomy. In general, small stones (less than 5mm) will take 1-2 weeks to pass on their own. Larger stones (greater than 5mm) may take 4-6 weeks to pass.

Stones that are located in the ureter (the tube that connects the kidney to the bladder) are more likely to become stuck and may require medical intervention to remove them. If you are experiencing pain or other symptoms associated with kidney stones, it is important to see a doctor for an evaluation.

Diagnosis of kidney stones

Diagnosing kidney stones usually begins with a physical examination and a review of your medical history. Blood tests and urine tests may also be ordered to assess kidney function and blood counts measurements. Your doctor will ask about your symptoms and may order one or more imaging tests to confirm the diagnosis.

Common imaging tests used to diagnose kidney stones include ultrasounds, CT scans and X-rays. Once diagnosed, treatment for kidney stones will vary depending on the size and type of stone you have. Small kidney stones may be treated with home remedies or by drinking plenty of fluids. Larger kidney stones may require surgery to remove them. If you have kidney stones your doctor can help you develop a treatment plan that is right for you.

Treatment options for kidney stones

Once you’ve been diagnosed with kidney stones, your doctor will work with you to develop a treatment plan that best suits your needs. In most cases the goal is to help you pass your stone without having to undergo surgery. Treatment options include:

  • Drinking plenty of fluids: Drinking enough water can help flush out small stones so they don’t get bigger. You may be advised to drink up to 3 litres daily until the stones clear. If your urine is dark it means you are not drinking enough water. Ideally, your urine should be pale in colour
  • Pain relievers: Taking over-the-counter pain relievers like ibuprofen or paracetamol can help manage the pain until the stone passes on its own. Prescription painkillers may be prescribed for severe pain
  • Alpha-blockers: Certain medications such as alpha-blockers (if the kidney stones are 5 to 10 millimetres in diameter) can help to relax the muscles and allow the stones to leave the body. Common side effects include low blood pressure, fatigue and dizziness
  • Allopurinol: Allopurinol is a medication that is used to treat kidney stones and works by reducing the amount of uric acid in the body. The allopurinol dose your doctor prescribes will depend on several factors, such as your kidney function and the severity of your kidney stones. If you have kidney stones, allopurinol may help to prevent new stones from forming. In some cases, allopurinol is used along with other medications to treat kidney stones

Surgery for kidney stones

In some cases surgery may be necessary to remove a large kidney stone that’s causing blockage or isn’t responding to other treatments. The main types of surgery for removing kidney stones are percutaneous nephrolithotomy, shock wave lithotripsy and ureteroscopy.

Percutaneous nephrolithotomy (PCNL) is a minimally invasive procedure during which a small incision is made in the back and a tube is inserted into the kidney. Then, sound waves are used to break up the stone and suction is used to remove the fragments.

During Extracorporeal shock wave lithotripsy (ESWL), the patient lies on a table, a machine sends shock waves to the kidney from outside the body. These shock waves break up the stones into small pieces that can then pass through the urinary tract.

Ureteroscopy is another minimally invasive procedure during which a thin flexible tube, equipped with a camera and light is inserted into the urinary tract. The camera allows the urologist to locate the stone and then special instruments are used to remove or break up the stone.

Treatment for kidney stones is typically performed by a urology specialist. Once diagnosed, your urologist will discuss your treatment options and help you choose the best option for you based on several factors including the size of the stone, location of the stone and your overall health.

While there’s no surefire way to prevent kidney stones from forming altogether, understanding the causes and risk factors can help you decrease your chances of developing them. If you do develop symptoms suggestive of kidney stones, don’t hesitate to see your healthcare provider right away. With early diagnosis and treatment, you can minimise your discomfort and get back to living your life!


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NowPatient has taken all reasonable steps to ensure that all material is factually accurate, complete, and current. However, the knowledge and experience of a qualified healthcare professional should always be sought after instead of using the information in this page. Before taking any drug, you should always speak to your doctor or another qualified healthcare provider.

The information provided here about medications is subject to change and is not meant to include all uses, precautions, warnings, directions, drug interactions, allergic reactions, or negative effects. The absence of warnings or other information for a particular medication does not imply that the medication or medication combination is appropriate for all patients or for all possible purposes.

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