Kidney Stones

Kidney Stones

What are kidney stones?

Kidney stones, or renal calculi, are solid masses made of crystals. They can develop anywhere along your urinary tract, which consists of the kidneys, ureters, bladder, and urethra. Kidney stones can be a painful medical issue. The causes of kidney stones vary according to the type of stones. Not all kidney stones are made up of the same crystals. The different types of kidney stones include:

Calcium

Calcium stones are the most common. They’re often made of calcium oxalate, though they can consist of calcium phosphate or maleate. Eating fewer oxalate-rich foods can reduce your risk of developing this type of stone. High-oxalate foods include:

Potato chips
Peanuts
Chocolate
Spinach

However, even though some kidney stones are made of calcium, getting enough calcium in your diet can prevent stones from forming.

Uric acid

This type of kidney stone is the second most common. They can occur in people with gout, diabetes, obesity, and other types of metabolic syndrome. This type of stone develops when urine is too acidic. A diet rich in purines can increase urine’s acidic level. Purine is a colorless substance in animal proteins, such as fish, shellfish, and meats.

Struvite

This type of stone is found mostly in people with urinary tract infections (UTIs). These stones can be large and cause urinary obstruction. Struvite stones result from a kidney infection. Treating an underlying infection can prevent the development of struvite stones.

Cystine

About 1 in 7,000 people worldwide get cystine kidney stones. They occur in both men and women who have the genetic disorder cystinuria. With this type of stone, cystine — an acid that occurs naturally in the body — leaks from the kidneys into the urine.

What are the symptoms and signs of a kidney stone?

Kidney stones can cause severe pain. Symptoms of kidney stones may not occur until the stone begins to move down the ureters. This severe pain is called renal colic. You may have pain on one side of your back or abdomen. In men, pain may radiate to the groin area. The pain of renal colic comes and goes but can be intense. People with renal colic tend to be restless. Other symptoms of kidney stones can include:

Blood in the urine (red, pink, or brown urine)
Vomiting
Nausea
Discolored or foul-smelling urine
Chills
Fever
Frequent need to urinate
Urinating small amounts of urine

In the case of a small kidney stone, you may not have any pain or symptoms as the stone passes through your urinary tract.

What are the causes of kidney stones?

Kidney stones are most likely to occur in people between the ages of 20 and 50. Different factors can increase your risk of developing a stone. In the United States, white people are more likely to have kidney stones than Black people. More men than women develop kidney stones. A history of kidney stones can increase your risk. So does a family history of kidney stones. Other risk factors include:

Dehydration
Obesity
A diet with high levels of protein, salt, or glucose
Hyperparathyroid condition (condition related to overactive parathyroid)
Gastric bypass surgery
Inflammatory bowel diseases that increase calcium absorption
Taking medications such as triamterene diuretics, antiseizure drugs, and calcium-based antacids

How are kidney stones are treated?

Treatment is tailored according to the type of stone. Urine can be strained and stones collected for evaluation. Drinking six to eight glasses of water a day increases urine flow. People who are dehydrated or have severe nausea and vomiting may need intravenous fluids. Other treatment options include:

Medication

Pain relief may require narcotic medications. The presence of infection requires treatment with antibiotics. Other medications include:

Allopurinol (Zyloprim) for uric acid stones
Thiazide diuretics to prevent calcium stones from forming
Sodium bicarbonate or sodium citrate to make the urine less acidic
Phosphorus solutions to prevent calcium stones from forming
Ibuprofen / paracetamol for pain
Naproxen sodium (Aleve) for pain

Lithotripsy

Extracorporeal shock wave lithotripsy uses sound waves to break up large stones so they can more easily pass down the ureters into your bladder. This procedure can be uncomfortable and may require anesthesia. It can cause bruising on the abdomen and back and bleeding around the kidney and nearby organs.

Tunnel surgery (percutaneous nephrolithotomy)

A surgeon removes the stones through a small incision in your back. A person may need this procedure when:

The stone causes obstruction and infection or is damaging the kidneys
The stone has grown too large to pass
Pain can’t be managed

Ureteroscopy

When a stone is stuck in the ureter or bladder, your doctor may use an instrument called a ureteroscope to remove it. A small wire with a camera attached is inserted into the urethra and passed into the bladder. The doctor then uses a small cage to snag the stone and remove it. The stone is then sent to the laboratory for analysis.

Pain management

Passing a kidney stone can cause pain and discomfort. Your doctor may recommend taking an over-the-counter pain reliever, such as acetaminophen or ibuprofen, to help reduce symptoms. Or stronger medications such as tramadol.

How is the diagnosis of kidney stones made?

Diagnosis of kidney stones requires a complete health history assessment and a physical exam. Other tests include:

Blood tests for calcium, phosphorus, uric acid, and electrolytes
Blood urea nitrogen (BUN) and creatinine to assess kidney functioning
Urinalysis to check for crystals, bacteria, blood, and white cells
Examination of passed stones to determine their type

The following tests can rule out obstruction:

Abdominal X-rays
Intravenous pyelogram (IVP)
Retrograde pyelogram
Ultrasound of the kidney (the preferred test)
MRI scan of the abdomen and kidneys
Abdominal CT scan

The contrast dye used in the CT scan and the IVP can affect kidney function. However, in people with normal kidney function, this isn’t a concern.

How long does it take to pass a kidney stone?

The amount of time that it takes to pass a kidney stone can vary depending on the size of the stone. Generally, small stones are able to pass through the urine within 1-2 weeks, often without any treatment. On the other hand, larger stones may take 2-3 weeks to move through the kidneys and into the bladder. Stones that don’t pass on their own within 4 weeks typically require medical treatment.

How can you prevent kidney stones?

Proper hydration is a key preventive measure. It’s recommended to drink enough fluid to pass at least 2.5 liters of urine each day. Increasing the amount of urine you pass helps flush the kidneys. You can substitute coconut water, lemon-lime soda, and fruit juice for water to help you increase your fluid intake. If the stones are related to low citrate levels, citrate juices could help prevent the formation of stones. Eating oxalate-rich foods in moderation and reducing your intake of salt and animal proteins can also lower your risk of kidney stones.

Foods that can cause kidney stones

In addition to drinking more water, making modifications to your diet could also help prevent kidney stones. Here are some foods that you may need to limit or avoid: beef, chicken, pork, organ meats (liver, gizzard), fish, shellfish, eggs, milk, cheese, yogurt, processed meats, fast food, frozen meals and salty snacks. Animal proteins like meat, poultry, seafood, and dairy products can increase levels of uric acid in your urine and increase the risk of developing kidney stones.

When to see a doctor

If you experience any of the following symptoms, you should seek immediate medical attention: