A kidney stone is a hard mass that forms in one or both your kidneys, from minerals and salts in the urine, and can cause severe pain if they are large enough. Kidney stones usually resemble small ”pebbles”. Studies suggest that one in every 20 people develop kidney stones at some point in their life.

Kidney stones usually form when there is a decrease in your urine volume and/or an excess of stone-forming substances in the urine.

Understanding Your Urinary System

Your urinary system, also known as the renal system or the urinary tract, consists of four main organs, namely the kidneys, ureters, bladder, and urethra. The foremost function of your urinary system is to eliminate wastes from your body.

  • Your kidneys make urine by filtering out wastes and extra water from the blood. 

  • Urine travels from your kidneys through the two thin tubes called ureters and fills up your bladder (a muscular, pear-shaped organ in your lower abdomen that stores urine).

  • Once your bladder is full, you urinate through the urethra to eliminate the wastes.

Formation of Kidney Stones

Kidney stones are mineral and salt deposits that form inside your kidneys. This condition is known as renal lithiasis or nephrolithiasis. 

Kidney stones form when your urine contains more crystal-forming substances than the fluid in your urine can dilute. At the same time, if your urine lacks substances that prevent crystals from sticking together, it creates an ideal environment for kidney stones to form.

Kidney stones can be of various types:

Calcium stones: Most kidney stones are calcium stones, usually in the form of calcium oxalate or calcium phosphate. Oxalate is an organic compound found in plants but is also synthesized by your body in the liver. Oxalate is found in certain fruits, vegetables, nuts, and chocolates. Your diet, intestinal surgeries, and several metabolic disorders (a cluster of conditions that occur together) can increase the concentration of calcium or oxalate in your urine.

Calcium phosphate stones are formed when you are taking medications for seizures and migraines or in certain metabolic disorders like renal tubular acidosis (RTA). In RTA, kidneys are unable to excrete acids into the urine which causes increased acids in the blood, leading to growth retardation, and the formation of kidney stones.

Uric acid stones: These types of stones are more common in males than in females. Uric acid stones are formed when you have gout (a form of arthritis where there is the deposition of uric acid crystals in the joints, causing pain, redness, swelling, and inability to walk) or if you are undergoing chemotherapy for cancer treatment. 

Uric acid is a waste byproduct produced by your body when it digests purines. Purine is a colourless substance found in animal proteins like meats, sardines, dried beans, and beer. A diet rich in purines can cause an increase in the acid content in your urine, causing the formation of uric acid stones. This type of kidney stone can also form when you lose too much fluid from your body, due to dehydration. 

Struvite stones: These are usually seen in women who have UTIs (urinary tract infections). These are large stones and cause blockage in the urinary tract, leading to kidney infections. If the underlying infection is treated, then the development of struvite stones can be prevented.

Cystine stones: These are the least common type of kidney stones. These occur due to a genetic mutation in which your kidneys have difficulty in reabsorbing a compound called cystine. 

Cystine is an amino acid produced by your body which forms building blocks of protein in the cells. When there is too much cystine in the urine, kidney stones can form.

Here are some of the major reasons behind the formation of kidney stones:

1. Low water intake. This can lead to dehydration, which is the leading cause of kidney stone formation. Low water/fluid intake can damage your kidneys and also result in the passage of less urine. Due to lack of enough water, the stone-forming crystals in your kidney will stick together easily and form kidney stones. 

When you urinate frequently, the excess fluid in your kidney passes any small stones that might be formed. Less frequent urination keeps the stones from moving away and they grow larger in size, resulting in pain from kidney stones.

2. Health conditions can also put you at a high risk of developing kidney stones. Some of these conditions include: 

  • Crohn's disease. It is an inflammation of your digestive tract that decreases your body’s ability to absorb fat, resulting in oxalate kidney stones 

  • Urinary tract infections (UTIs). It is an infection that can occur in any part of your urinary system, leading to the formation of kidney stones.

  • Hyperparathyroidism. This is a condition in which your parathyroid glands (4 small glands that regulate the amount of calcium in your body) release too much parathyroid hormone (PTH) in your blood. PTH increases calcium in your body and can cause calcium or oxalate kidney stones.

  • Medullary sponge kidney (MSK). This is a congenital disorder (defect presented at birth) in which cysts are formed on either side of the collecting tubes within your kidney. If you suffer from MSK, the risk of kidney stones is higher in you. 

  • Dent's disease. This is a rare genetic kidney disorder in which there are increased levels of calcium in your urine, which leads to the formation of calcium stones.

  • Renal tubular acidosis (RTA). It is a condition in which your kidneys fail to filter acid from your blood and excrete it through your urine. 

3. Medications prescribed for seizures (sudden, uncontrolled electrical disturbances in your brain) and migraines (recurrent attacks of moderate to severe throbbing pulsating headache) may also increase the likelihood of developing kidney stones.

4. Other risk factors include a family history of kidney stones, obesity (excess accumulation of fat in your abdominal region), an unhealthy diet, gastric bypass surgery (a type of weight loss surgery), and chronic diarrhoea (passing of watery stools for more than 3 weeks, leading to severe dehydration).

Symptoms of Kidney Stones

  • Severe pain in your back or abdomen

  • Blood in the urine (red, pink, or brown urine)

  • Nausea

  • Strong, foul-smelling urine

  • Chills

  • Fever

  • Frequent urge to urinate

  • Urinating small amounts of urine 

Complications Due to Kidney Stones

  • When the stones move from the kidneys into the uterus and create a blockage in the ureters

  • When the stones are large in size and cause severe abdominal pain

  • When you pass blood in your urine

  • When the stones cause a blockage in your urine, known as urinary obstruction

Diagnosis and Treatment

Diagnosis of kidney stones require physical tests and examinations such as:

  • Abdominal X-rays

  • Ultrasound of your kidney (the preferred test)

  • MRI (Magnetic resonance imaging) scan of your abdomen and kidneys

  • Abdominal CT (computerized tomography) scan

  • Blood tests

Treatment depends upon the type and size of the kidney stone, and your symptoms. Treatment options range from medications to surgery to dissolve/pass or remove the kidney stones. Consult your physician to understand the best line of treatment for you.

Can You Prevent The Formation of Kidney Stones? 

If you are diagnosed with kidney stones, your doctor will give you tips on how to prevent their formation in the future. Simple dietary and lifestyle recommendations can prevent kidney stone formation. These tips include:

1. Drink lots of fluids. The easiest way to prevent kidney stone formation is by staying hydrated throughout the day. It is recommended to have 2-2.5 liters of water if you don't suffer from heart or liver diseases. 

A lower water intake will result in low urine; your urine will also become highly concentrated and this will prevent the urine salts from dissolving. They thus accumulate and form kidney stones. 

Try to have citrus juices like lemonade and orange juice. The citrate present in these juices will help inhibit the formation of crystal stones. 

2. Lower your sodium (salt) intake. High levels of salt in urine may prevent calcium reabsorption from the urine to the blood. This leads to a high accumulation of calcium in the urine, resulting in the development of kidney stones. 

Avoid high-sodium foods such as processed foods (chips, salty biscuits), canned soups and vegetables, condiments (mustard, soy sauce, etc.), and foods containing baking soda and monosodium glutamate (MSG). MSG is a taste enhancer added to Chinese foods, canned soups, and vegetables, which can cause the formation of stones. 

3. Eat calcium-rich foods. Contrary to popular belief, a diet low in calcium can actually increase your risk of having kidney stones. This happens due to increased oxalate levels in the body. Oxalate is a natural substance present in foods such as beans, beets, and dark leafy vegetables. With no calcium to bind with, oxalate levels peak in the body, thus creating kidney stones. 

Natural sources of calcium, like milk or paneer, are recommended to maintain calcium levels in your body. However, you should avoid taking excess calcium supplements as they can increase the chance of kidney stone formation.

4. Avoid kidney stone-forming foods. The consumption of foods rich in oxalates can increase your risk of getting kidney stones. This is because oxalate is a natural compound found in foods that bind with calcium in the urine, thereby, forming kidney stones. 

Foods rich in oxalates include chocolates, spinach, coffee, black tea. Having fewer of these foods can help reduce the risk of kidney stones.

5. Limit your meat intake. Daily consumption of high amounts of meat can result in an increased risk of developing uric acid problems and kidney stones. Limit your intake of beef, fish, pork, and poultry to avoid the risk.

 Consult your doctor or dietitian for the amount and kind of meat you can consume on a weekly basis because completely cutting down your protein (meats are an important source of protein) intake is not advisable as this leads to weakness in the body.

6. Avoid vitamin C supplements. Natural vitamin C from foods such as oranges, lemons, grapefruit, strawberries, papaya, broccoli, and cauliflower is a good addition to your diet. However, vitamin C supplements pose a high risk of kidney stone formation. 

Consuming too much vitamin C can increase the amount of oxalate in your urine, thus increasing the risk of developing kidney stones. 

Kidney stones are not a serious issue unless they are large in size and are causing you immense amounts of pain. 

Staying hydrated and eating the right amount of food can help prevent kidney stone formation. Consult your physician/ urologist to understand other underlying causes and prevention of kidney stones. 

Disclaimer: This article is written by the Practitioner for informational and educational purposes only. The content presented on this page should not be considered as a substitute for medical expertise. Please "DO NOT SELF-MEDICATE" and seek professional help regarding any health conditions or concerns. Practo will not be responsible for any act or omission arising from the interpretation of the content present on this page.