Kidney stones: definition, symptoms, diagnosis and treatment

By Cristiano Antonino On Apr 7, 2023

Kidney stones (also called nephrolithiasis or renal lithiasis) are deposits of mineral salts that form in the urinary tract

Diet, excess body weight, certain medical conditions, and some medications can all contribute to its formation.

Kidney stones can be located anywhere in the urinary tract, from the kidneys to the bladder

They often form when urine becomes concentrated, allowing minerals to crystallize and stick together. Passing the calculations can be quite painful.

Depending on the situation, taking pain relievers and drinking lots of water may be enough.

In other cases, for example when they are deposited in the urinary tract, hindering the physiological flow of urine, they can cause complications requiring surgery.

Kidney stones: definition and what they consist of

The precipitation of mineral salts present in the urine causes deposits called kidney stones.

Calcium, oxalate, phosphates and uric acid are transformed into stones either due to the increase in their concentration in the urine or due to the reduction of the liquid which holds them in solution.

Initially the salts by aggregating determine the formation of so-called crystals (microstones), which subsequently unite in stones and can move and get to hinder the outflow of urine.

This can lead to the development of urinary infections, which when recurrent can lead to progressive damage to the kidneys up to renal failure.

Kidney stones: symptoms

A kidney stone usually doesn’t cause symptoms until it moves inside the kidney or passes into the ureters, the tubes that connect the kidneys and bladder.

Depositing in the ureters, it can block the outflow of urine, causing swelling of the kidney (hydronephrosis) and spasm of the ureter, which can be very painful.

At that point, the patient may experience several signs and symptoms:

severe sharp pain in the side and back,
pain radiating to the lower abdomen and groin
pain intermittent and fluctuating in intensity
pain or burning sensation when urinating

Other signs and symptoms may include:

pink, red, or brown urine
foul-smelling urine
a persistent need to urinate, urinating more often than usual, or urinating in small quantities
nausea and vomit
fever and chills if an infection is present

The pain caused by a kidney stone can change, such as moving to a different location or increasing in intensity, as the stone moves through the urinary tract.

The causes of kidney stones and how to prevent them

Kidney stones often don’t have a single, defined cause, although several factors can increase your risk of suffering from them.

They form when urine contains more crystal-forming substances (such as calcium, oxalate, and uric acid) than the liquid in which they are contained can dilute.

At the same time, urine may be free of substances that prevent crystals from sticking together, creating an ideal environment for stone formation.

Types of kidney stones

Knowing the type of kidney stones helps determine the cause and can provide clues on how to reduce the risk of developing others later.

Here are the types available:

Calcium Stone. Most kidney stones are calcium stones, usually from calcium oxalate. Some fruits and vegetables, as well as nuts and chocolates, are high in oxalates.

Dietary factors, high doses of vitamin D, intestinal bypass surgery, and various metabolic disorders can increase the concentration of calcium or oxalate in the urine.

Calcium stones can also be made up of calcium phosphate.

This type of stone is more common in metabolic conditions, such as renal tubular acidosis.

It can also be combined with some medications used to treat migraines or seizures, such as topiramate (Topamax).

Struvite stones. They are formed as a result of urinary tract infections.

These can grow quickly and become quite large, sometimes with few symptoms.

Stones of uric acid. They can form in people who lose a lot of fluids due to chronic diarrhea or malabsorption as well as in those who follow a diet rich in proteins and in patients with diabetes mellitus or metabolic syndrome.

Certain genetic factors can increase the risk of developing them.

Cystine stones. They usually affect people with an inherited disorder called cystinuria, which causes the kidneys to excrete too much cystine, an amino acid.

Kidney stones, risk factors

Factors that increase your risk of developing kidney stones include:

Family or personal history. If someone in the family has had kidney stones, one member is more likely to develop them. Furthermore, those who have already suffered from it in the past are more at risk of developing others.
Dehydration. Not drinking enough water every day can increase your risk of kidney stones. People who live in hot, dry climates and those who sweat a lot may be more at risk than others.
Diets. Eating a diet high in protein, sodium (salt), and sugar can increase your risk of developing some types of kidney stones.
Obesity. High body mass index (BMI), large waistlines and weight gain have been linked to an increased risk of kidney stones.
Digestive diseases and surgery. Gastric bypass, inflammatory bowel disease, or chronic diarrhea can lead to increased urinary excretion of stone-forming substances.
Other medical conditions such as renal tubular acidosis, cystinuria, hyperparathyroidism, and repeated urinary tract infections can increase the risk of kidney stones.

Certain supplements and medications, such as vitamin C, dietary supplements, laxatives (if used excessively), calcium-based antacids, and some medications used to treat migraine headaches or depression can increase the risk of kidney stones.

Kidney stones, the diagnosis

If the doctor suspects that the patient has a kidney stone, he or she usually runs tests and diagnostic procedures such as:

Blood analysis. Blood tests are often normal, but can sometimes reveal too much calcium or uric acid in the blood. Blood test results also help monitor kidney function.
Urinalysis. It is useful to check for crystals in the urine as well as to rule out the possible presence of a urinary tract infection.
Imaging. Imaging tests can show kidney stones in the urinary tract. Computed tomography (CT). Plain abdominal radiographs are used less frequently because this type of imaging test may miss some types of stones as well as those that are volumetrically smaller.
Ultrasound. A non-invasive test that is quick and easy to perform, is another possible option for diagnosing kidney stones.
Calculation analysis. The patient may be asked to urinate through a strainer to collect the expelled stones. The laboratory analysis will reveal the composition of the kidney stones. Your doctor uses this information to determine the cause of your kidney stones and to make a plan to prevent them from forming again.

The most effective treatments to fight kidney stones

Treatment for kidney stones varies depending on the type of stone and the cause.

Small stones with minimal symptoms

Most small kidney stones do not require invasive treatment.

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The patient can easily pass the stone by urinating by assuming specific behaviors:

Drink plenty of water: Drinking 1.8 to 3.6 liters of water a day keeps urine diluted and can prevent stones from forming. Unless the doctor instructs otherwise, the patient should drink enough fluids (mostly water) to produce clear or nearly clear urine;
take painkillers: the passage of a small stone can cause some discomfort. For mild pain relief, your doctor may recommend pain relievers such as ibuprofen or naproxen sodium
medical therapy. Your doctor may prescribe a medicine to help you pass the stones. This type of drug, known as an alpha blocker, relaxes the muscles in the ureter, helping the person pass the stone more quickly and with less pain.

Large stones and stones that cause symptoms

Kidney stones that are too large to pass on their own or that cause bleeding, kidney damage, or urinary tract infections require more extensive treatment.

Procedures may include:

use shock waves to break up stones. For some kidney stones, depending on their size and location, your doctor may recommend a procedure called “extracorporeal shock wave lithotripsy.”
surgery to remove very large stones in the kidney. The procedure called “percutaneous nephrolithotomy” involves the surgical removal of a stone, using small instruments inserted through a skin incision
endoscopy. To remove a smaller stone from the ureter or kidney, doctors may pass a thin endoscope (ureteroscope) equipped with a camera through the urethra and bladder. Once the stone is located, tools can trap it or break it into fragments that will then pass into the urine. Doctors may then place a small tube (stent) in the ureter to restore patency of the urinary tract and help urine flow properly. General or local anesthesia may be required during this procedure.
parathyroid gland surgery. Some calcium phosphate stones are caused by overfunctioning parathyroid glands, which are located in the four corners of the thyroid gland, just below the Adam’s apple. When these glands produce too much parathyroid hormone (hyperparathyroidism), the calcium levels in the blood and urine can become too high, resulting in kidney stones. Hyperparathyroidism sometimes occurs when a small, benign tumor forms in one of the parathyroids. The removal of the gland in this case is decisive.

How to prevent the development of kidney stones

To avoid the development of kidney stones, one must adopt certain habits. Here is a list of what you should do:

Drink water all day: For people with a history of kidney stones, doctors recommend drinking enough fluids to pass about 2 liters of urine per day. Your doctor may ask you to measure your urine output to make sure you are drinking enough.
if you live in a hot, dry climate or exercise frequently, you must drink even more water to produce enough urine. If your urine is clear and clear, you are probably drinking enough.
eat fewer oxalate-rich foods. These include rhubarb, beets, spinach, Swiss chard, sweet potatoes, nuts, tea, chocolate, black pepper and soy products.
choose a diet low in salt and animal proteins: reducing the amount of salt you eat and choosing non-animal sources of protein, such as legumes, is a good habit.

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