kidney stones and kidney disease

Kidney stones- A beginers guide for patients


What are kidney stones?

Kidney Stones are solid materials that develop from substances dissolved in high concentration in urine. Kidney stones may remain in the kidney or break loose and move down the urinary tract to be passed in the urine. Sometimes kidney stones may form in the bladder. Depending on the size of the stone, the stone may pass freely into the urine with or without symptoms. On other occasions, the stone gets trapped along the urinary tract causing pain, blockage to the free flow of urine or other problems.

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Figure 1: Kidney stones may develop anywhere along the urinary tract. They may form in the kidneys, the ureters or the bladder.

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Figure 2: Kidney stones vary in size from being invisible to the eye to being as large as a finger nail. Small stones or large stones are still capable of causing symptoms. Larger stones are most painful and problematic.

How common are kidney stones?

Even though kidney stones are less common in Africans compared to white people, kidney stones occur fairly frequently among Nigerians and it is estimated that about 65,000-130,000 new cases occur every year in Nigeria. Several hundred thousand Nigerians with longer histories of kidney stones live with kidney stones occurring predominantly in men and in those between the ages of 20 and 45 years of age.  Once a person develops the first kidney stone, he or she is more likely to develop additional stones.

The number of people suffering from kidney stones every year is increasing. The reasons for this are not entirely clear but changing food intake and better diagnostic capability are considered likely causes.

Who gets or develops kidney stones?

Increasing body weight, diabetes, hot temperatures, excessive salt and protein intake and insufficient water intake are considered risk factors for developing kidney stones as well.

The typical person with a kidney stone is a heavy Nigerian male between the ages of 20 and 45 years with a family history of kidney stones who lives in the northern part of the country and works outside most of the time.

It is interesting to note that obese people and diabetic patients have a lower urine pH and a higher urinary uric acid excretion putting them at increased risk  of developing uric acid kidney stones

What are the kinds of kidney stones?

It is important to know that there are different kinds of kidney stones because the treatments for a particular kind of kidney stone may be different from treatments for other kinds of kidney stones. Some patients may have mixed types of kidney stones.

The most common kind of kidney stone is a calcium stone. For patients with calcium stones, the calcium in the urine combines with substances like oxalate or phosphate to form a salt crystal in the urine that can grow and form a large stone. Calcium is an important substance needed for giving strength to bones and teeth, and important in muscle and heart contraction, blood clotting, food digestion, nerve function and many other functions. Free calcium in the blood is filtered by the kidneys into the urine and if calcium accumulates in excess in the blood or urine, it can increase the risk of kidney stone formation. Concentrated urine, excessive amounts of oxalate and uric acid in the urine or low amounts of citrate in the urine are risk factors for developing calcium stones.

Struvite stones form in patients who have infections in the urinary tract with ammonia producing microorganisms. Usually involves gram negative bacteria that are urea splitting . Highly alkaline urine and a high urinary magnesium load can predispose to struvite stones in the presence of the right bacteria. These stones can grow to be very large, may need surgical removal and often need treatment with long term antibiotics along with other measures to control or prevent them.

Cystine stones result from a genetic disorder called cystinuria that causes cystine to leak through the kidneys and into the urine, forming crystals that tend to accumulate into stones. These stones can be hard to find even on x-ray. Cures do not exist but they can be managed effectively by a good doctor.

Uric acid stones develop in people who over produce uric acid or with normal uric acid concentrations but with high urinary uric acid excretion. Some genetic disorders of metabolism as well as gout can be associated uric acid stones. Some blood cancers and defects in kidney handling of uric acid can also predispose to uric acid stones. Low urine pH increases the likelihood of developing a uric acid stone.

Excessive excretion of oxalate in the urine may also be a cause of kidney stones. This excessive excretion may be genetically inherited with treatment ranging from vitamin B6 administration for mild disease to simultaneous liver-kidney transplant for patients with severe disease often leading to kidney failure. On other occasions, the excretion of oxalate in high quantities into the urine may be due to other disorders such as poor intestinal absorption of fatty and bile acids.

Other uncommon causes of kidney stones occur in patients with cystic fibrosis, in those taking the HIV drug called indinavir or in those taking excessive amounts of Vitamin C

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Figure 3: Types of kidney stones. Kidney stones can come in different colors, sizes and shapes. Sometimes they can be mixed. Different types of stones require different types of treatment.

Top left- Brushite/Apatite stones, Top right- Struvite stones, Middle left- Calcium oxalate stones, Middle right- Cystine stones, Bottom left- Uric acid stones, Bottom right- Mixed type stones.

What are the symptoms, signs and complications of kidney stones?

Symptoms of kidney stones might include some or all of the following

  • Pain in the abdomen or groin,
  • Bloody urine,
  • Nausea, vomiting and frequent urination,
  • Cloudy  or smelly urine
  • Fevers and body shaking if associated with infection of the urinary tract.
Locations for kidney stone pain

Figure 4: Locations for kidney stone pain. The pain often is only on one side but may be on both sides.

Signs of kidney stones that may be detected by a medical professional include

  • Tenderness in the lower back, abdomen or bladder regions
  • Decrease intestinal activity
  • Painful groin or testicles
  • High heart beat or blood pressure
  • Fevers and chills

Complications of kidney stones include

  • Urinary tract obstruction
  • Urinary tract infection including abscess formation
  • Perforation along the urinary tract and leakage of urine
  • Urinary fistula formation
  • Increased risk for kidney disease and kidney failure due to obstruction or infection
  • Increased risk of hypertension which in turn can damage the kidneys.

How do I know if my symptoms are from a kidney stone? Could it be from something else?

Do not assume that all abdominal pain is due to a kidney stone. It is important that you go to see a doctor so that a proper diagnosis can be made because if the wrong diagnosis is made, it may be life threatening. Important other diagnoses to be considered include

  • Abdominal aortic aneurysm
  • Appendicitis
  • Gall bladder infection or gall stone disease
  • Diverticulitis- inflammation of the colon
  • Gastric or duodenal ulcers
  • Liver abscess
  • Pancreatitis
  • Testicular torsion or epididymitis

What tests can be performed to determine if I have kidney stones?

A number of tests need to be performed to determine

1)      if your symptoms are due to kidney stones,

2)      if there are complications due to the kidney stones

3)      what kind of kidney stone you have

4)      the best sort of treatment to offer you.

Tests should be performed on your urine and blood. Special x-rays, CT scans or ultrasound tests may need to be performed to determine the size and location of the stone or if there are any complications of the stone such as abscess for fistula formation. A good doctor will ask you to bring in a sample stone if possible for detailed analysis of the stone type or ask you to perform a collection of all urine passed in a 24 hour period to determine the type of urine abnormality leading to stone formation.

How are kidney stones treated?

Treatment of kidney stones involves medical treatment and at times surgical management. Depending on the situation, this may need to be provided on an emergency basis.  Some cases will need hospital admission while sometimes the situation can be managed on an outpatient basis.

  • Fluid hydration. You need to take at least 3 liters of water every day to help prevent formation of more stones and help dissolution of existing stones
  • Treating possible infection with antibiotics
  • Pain control- with medication or with emergency stenting or drainage.
  • Attempts at medical management to enable passing the stone without surgery can be planned by your kidney specialist or urologist. It is not always successful.
    • The medical management often involves fluid hydration, drugs to help relax the urinary tract and enable passing of the stone in the urine, reducing calcium, oxalate or uric acid excretion into the urine, increasing substances in urine to help prevent and dissolve stones. Those with struvite stones in addition to antibiotics may need to be treated with drugs that inhibit some of the activity of urea splitting bacteria while those with cystine stones may need additional treatment with a binding agent that increases the dissolution of  excess cystine in the urine.
    • There often is a need to modify your diet to reduce the amount of stone forming substances in your urine. For example, kidney stone patients need to significantly reduce their salt and animal protein intake. For patients with oxalate stones, reducing the amount of oxalate intake in food such as is seen in chocolate and spinach and other green leafy vegetables is recommended. patients with uric acid stones need to reduce their intake of organ meats.  There is often no need to reduce the amount of calcium in the diet as long as 
    • Weight loss and better control of diabetes may also be important in some patients especially those with uric acid stones.

Your doctor will determine which drugs, diet and lifestyle changes are necessary for you to undertake  depending on the type of stone you have.

  • When a stone is too big or medical non-surgical attempts at passing the stone have failed, or there are significant complications, surgical treatment is required and can range from
    • Stenting or urinary diversion
    • Open surgery
    • Ultrasound blasting/dissolution of the stone(s)
    • Video assisted removal of the stone often by passing a scope into the bladder and upwards into the urinary system

Make sure you see a well trained doctor to advise you on whether you have kidney stones, what type of kidney stone you have and what the proper treatment is. Not all kidney stones are treated the same way. Always ask about your options and what you can do to prevent kidney stones.