KIDNEY STONES - CAUSES, DIAGNOSIS & PREVENTION

KEY POINTS

• Calcium, oxalates and uric acids are responsible for most types of stones.

• Citrate helps in preventing stones.

• About 10% people have stones and the incidence is rising.

• Severe pain in the sides and blood in urine are common symptoms of kidney stones.

• CT scan is the best investigation to diagnose but Sonography is the first investigation that is done.

• Calcium supplements do NOT increase your risk of stone formation.

• Reduce your risk of stone formation by have more of water and vegetarian diet and less of animal proteins.

• Following an active healthy lifestyle also helps in preventing stone formation.

How Kidney Stone Form?

Urine holds many dissolved substances that the body is trying to throw out. Some of them can form stones like

• calcium,

• oxalate,

• uric acids.

When these substances become too concentrated in the urine, they form crystals.

Continued build-up of these substances around the crystals it leads to the stone formation. This is similar to the way in which a pearl is formed in an oyster.

Most of times these substances do not form stones. This is because body also has chemicals in urine (like citrate) which will suppress the formation of stone. But when these natural defence mechanisms against stones are overwhelmed, kidney stones may form.

Kidney Stones - Causes

Kidney leaks calcium:

Sometimes the kidneys leak calcium for no particular reason. The excess calcium in urine then causes stone formation.

This excess excretion of calcium can also happen in patients with hyperparathyroidism (increased secretion of a hormone called parathyroid hormone). However, in majority of cases no particular cause is found for excess excretion of calcium.

Excess uric acid in blood

Very frequently, this is because of consuming a large amount of animal protein. Animal protein increases the uric acid level in blood. This will lead to an excess uric acid excretion in the urine.

A non-vegetarian diet will also make the urine more acidic. As the acidity increases, less and less and less uric acid dissolves in urine. This insoluble uric acid will crystallize to form stone.

Less of CITRATE in urine.

Citrate is a key factor that reduces the stone formation.

Citrate will bind with the calcium so that now it is unavailable to form the stone. Some people just have low citrate in urine leading them to form stone again and again.

Anatomic conditions causing urine stagnation

Any condition which will not allow urine to drain normally, increase the chances of stone formation like:

• PUJ obstruction,

• ureteric stricture,

• calyceal diverticulum.

Incidence of Stone in General Population

A lot of people have kidney stones. In fact, an estimated 10% of people suffer from stone at some point in their life.

Stone are much more common in men than in women.

With the adoption of western non-vegetarian diet, the incidence is increasing in India.

Symptoms of Kidney Stones

A lot of kidney stones do not cause any symptoms. They silently lie in a corner in the kidney.

Stones usually cause symptoms when they block the flow of urine.

Pain

Sometimes the pain is so severe that the patient cannot find a comfortable position and keeps thrashing in bed. Typically, the pain starts in the sides and goes towards the front of the abdomen or to the groin area.

Reddish Urine

Urine may appear reddish due to blood in urine.

Other uncommon symptoms

People with diabetes and women are at an increased risk of infection. As such patients may develop fever due to infected urine that becomes trapped behind a stone. This is a serious infection situation and needs to be treated on an urgent basis.

Kidney stone passing out / dissolve (?)

Once a stone forms in the kidney it is not likely to dissolve. The only exception is uric acid stones that may dissolve with medicines.

But the good news is a lot of stones do pass out naturally. The bigger the stone the less likely it is to pass out. As a rule of thumb, stone that are less than 5 mm will generally pass out and stones that are more than 10 mm will not pass out.

The stone that is moving is likely to pass out. If the stone is not moving down for more than 2-3 weeks, it is not likely to pass out.

How are kidney stones diagnosed?

CT-Scan

Non-contrast CT scan (no contrast medium is given) is the best investigation to diagnose a kidney stone. However, because CT scan involves use of X-rays and exposure to radiation, an ultrasound or sonography is more likely to be done initially. If the ultrasound detects something that needs further clarification, then a CT scan is advised.

Blood tests

These include Blood urea and Creatinine to know the overall kidney function. CBC to exclude signs of infection throughout the body.

Urine Tests

Urine routine will give an overall picture if anything is wrong. Urine for culture may be advised if urine infection is suspected.

Other tests

 may be advised if required as per the condition of the patient.

Role of CT-Scan in diagnosis of kidney stones

The role of CT scan is:  

• Detection of stone.

  • It will detect almost all types of urinary stones.

• Detection of complications

  • Help in diagnosing infection in presence of the stone.

  • May rule out damage to kidney due to stones.

• 3 D reconstruction of the urinary system

  • helps in planning the treatment of the stone.

Some stones are very complex and need proper treatment planning for optimal results. So, patient may be informed about the success rate and complications in case of surgery.

Kidney stone and Calcium supplements

Calcium supplements are NOT likely to increase the incidence of stones.

This is because the stone formation is due to excess leakage of calcium in urine and not because of high intake of calcium leading to increase in calcium levels in blood.

Calcium levels in blood are very tightly regulated and if the calcium levels drop the body will just pull out the calcium from the bones.

Kidney Stones – Need for Treatment

Not all kidney stones need to be removed.

Stone removal is advised to care of the pain and / or take care (protect) the kidney.

• Pain

  • severe and not responding to pain medications.

• Protect the kidney

  • In presence of Infection

  • Stone that has got stuck and putting pressure on the kidney.

  • If the person has stone in single kidney

  • If the person has stone/s in both of the kidneys and it is expected that may cause problems.

• Removal For Non-Medical Reasons

  • Person who is working on Ship / Airlines. He will not likely to receive medical clearance to join duty.

  • Personal choice e.g. removal before travelling to a foreign country

    
    

Chance of developing a stone again

While, some people will form stones only once, about half of them are likely to form stones again. Then, there are a few who keep forming stones every 1-2 years.

Risk factors for kidney stones!

Dehydration

This is the most important factor and at the same time very easy to overcome. When you do not consume enough fluids during the day, the urine will become concentrated. This increases the chance that crystals can form from materials within the urine.

Drinking water will reduce the crystal formation.

Also, in case the crystals have formed there is a good chance that they will be flushed out before they enlarge and cause problem.

Diet

This is the second risk factor.

• High animal protein diet

• Increase uric acid levels in the body.

• Drinking sodas (Coca cola etc.) also increases the risk of stone formation.

  
  

Family history in First degree relatives

A person who has a first-degree relative (parent or sibling) with history of stone formation is much more likely to form a stone.

Metabolic Syndrome

Name given to a condition where a person is overweight and has:

• Waist circumference more than 40 inches in men and 35 in women

• Elevated levels of Triglyceride (cholesterol) in blood

• Diabetes (actual or borderline)

• High BP.

• Not only are such patient at increased risk of heart disease, but they are also at increased risk to form kidney stone.

  
  

Kidney Stone Prevention

Diet:

• Less of meat and more of vegetarian diet.

• Salt reduction in diet will also help.

Fluids:

• 2.5 – 3 litres of fluids per day is generally advised in reducing the recurrence of stones. It can be in form of

  • plain water,

  • barley water,

  • tender coconut water.

  • Lemon juice

• may help increasing the citrate in urine reduce the incidence of stones.

Healthy Lifestyle

Daily exercise to maintain a healthy lifestyle and ideal body weight to avoid Metabolic syndrome.