Kidney Stones: Types, Symptoms, Causes & Diagnosis

What are kidneys and their function?

Kidneys are two reddish-brown bean-shaped organs on either side of the spine in the abdomen. They are roughly the size of the fist or about 10 to 15 cm. The primary function of the kidneys is to filter out any waste from the blood. The waste is then excreted from the system in the form of urine.

What are kidney stones?

Kidney stones (also known as renal calculi or nephrolithiasis) are a common occurrence in most people. They are hard mass made of minerals, chemicals, and salts found in the urine. Usually, these substances—calcium, oxalate, urate, cystine, xanthine, and phosphate—get dissolved in the urine. But sometimes they become so concentrated that they turn into crystals and harden in the interior surface of the kidneys.
Kidneys stones can be as small as pebbles or a grain of sand and as big as a golf ball. After the stone is formed, it may stay within the kidney or flow to the ureter. Small stones can easily pass through the urine on their own and often do not elicit any pain. However, bigger kidney stones can cause significant discomfort, and might need surgical intervention for removal.

There are four types of kidney stones:

• Calcium stones: Majority of the kidney stones are calcium stones, made of calcium oxalate. The liver produces oxalate, and this substance is also absorbed from the food. Oxalate levels are high in some fruits and vegetables, in addition to nuts and chocolate, which can lead to the formation of calcium oxalate kidney stones. Oxalate concentrations can also rise because of high vitamin D dosages, intestinal bypass surgery, and some metabolic disorders. Calcium phosphate kidney stones are another type of calcium stone but are not as common as the calcium oxalate stone. This type of stone occurs to those with metabolic conditions like renal tubular acidosis. It could also be linked to medications for treating migraines or seizures.
• Struvite stones: Few kidney stones are comprise struvite, which is a mix of ammonium, magnesium, calcium carbonate, and phosphate. These stones are usually formed in response to a bacterial infection like a urinary tract infection. The bacteria behind these infections produce ammonia, which then increases the urine’s pH, making it alkaline in nature and leading to the formation of struvite. These types of stones are not very common.
• Uric acid stones: This is another commonly occurring type of kidney stones, which can happen after the consumption of foods like shellfish and red meat that contain a substance called purine. Those who have a high-protein diet, diabetes, or a metabolic disorder are also susceptible to uric acid stones.
• Cystine stones: These stones are uncommon and only occur in people who have cystinuria, a genetic metabolic condition that results in high cystine concentrations in the urine.

Causes of kidney stones

There is no singular cause behind the formation of kidney stones. Drinking inadequate amount of water, exercising a lot or not at all, obesity, weight-loss surgery, or consuming food high in salt or sugar are all possible causes. Infections and genetic predisposition can play a role in some people. Consuming too much fructose (commonly found in packaged foods like cold drinks, candy, and fruit juices) raises the chance of getting kidney stones.

Symptoms of kidney stones

Small kidney stones can go unnoticed, and a person having a small kidney stone will experience next to no discomfort. Mostly, people will pass them out through the urine without any issue. It’s the bigger kidney stones that are a cause for concern and can impede the quality of life. Kidney stone pain can be severe to the point it becomes unbearable.

The symptoms one should be on the lookout are:

• Kidney stone pain, usually on either side of the lower back
• Blood in urine (the urine colure can also be pink, brown, or red)
• Nausea and vomiting
• Constant urge to urinate but unable to go
• Burning sensation while passing urine
• Cloudy urine and/or foul-smell of the urine
• Fever and chills

Kidney stone pain and the above listed symptoms are not something anyone should take lightly. Hence, immediately seeing a doctor can help alleviate the symptoms and bring relief.

Diagnosing kidney stones

Recognising the symptoms and relaying them to a doctor is the first step towards a diagnosis. A physical history, which includes the symptoms a person has along with how long the symptoms have persisted are crucial. The doctor will also take information of any previous medical illness, any medications taken, family history, and the dietary history. They will also perform a physical exam to check for any pain in the groin or even abdomen.
However, to get a crystal-clear picture of the condition including the cause behind the renal calculi, the doctor may order the following tests:

Blood test: This is one of the most straightforward ways of testing for calcium and uric acid levels in the blood. Blood tests will help the doctor understand the type of kidney stone one has and determine the cause behind it. The sample is taken through a vein in the arm and then sent to a lab for examination.
With LivLong, anyone can sign up for a Kidney Function Test, which can provide the details of urea, uric acid, creatinine, and the urea/creatinine ratio in the blood. One requires no special preparation before the blood sample is collected. The price of a KFT test depends on the city of residence in and lab service chosen. The results will be shared within 24 hours.

Urine test: In a urinalysis, a person will have to collect their urine samples for the doctor to determine whether there is a high level of any minerals and salts causing kidney stones. This analysis can also help detect the presence of any bacterial infection that may have led to the formation of kidney stones.

Imaging tests: Besides the abovementioned methods, imaging tests are helpful in giving a complete picture of kidney stones like their exact size and shape. Imaging tests are also helpful in the case of painless kidney stones. Ultrasound and X-rays like the KUB x-ray (kidney-ureter-bladder x-ray) can show the doctor the size and location of the stones. Typically, KUB is used before and after the treatment course, and CT scan is done to arrive at a concrete diagnosis.

Treatment of kidney stones

The treatment course for kidney stones is the same for adults and children. Drinking sufficient water is advised so that a patient is not dehydrated and can pass the stone via urine without going under. Then, there is medication that reduces the amount of uric acid in the blood. Alpha blockers may be prescribed that relax the ureter and allow the stone to pass without any discomfort or pain.

Most kidney stones are sufficiently small to pass through the urine, and the symptoms may be easy to treat at home with medicines. Bigger stones might have to be dissolved or surgically removed.

The thought of undergoing surgery may be daunting but there has been significant improvement in surgical interventions for kidney disease. Patients are no longer required to stay in hospital post-surgery and the recovery time is also quick.

The common surgical procedures for kidney stone removal are:

Shock wave lithotripsy (SWL): This method uses high-frequency sound waves directed at the nephrolithiasis to break them into pieces small enough to pass with the urine. This can be uncomfortable so painkillers may be given ahead of time. One session is sufficient to remove the kidney stone.

Ureteroscopy: A thin lighted telescope with a camera is passed through the urethra and bladder. The surgeon can either use another instrument for the stone removal or break it apart with laser. This procedure is performed under general anaesthesia.

Percutaneous nephrolithotomy (PCNL): In this method, a thin telescope-like device called the nephroscope is passed through a small incision in the back to the kidney. Special instruments are used to break the stone apart. This procedure is also performed under general anaesthesia, and the patient may be required to stay in the hospital for a day or two.